Wellbore Plug Isolation System and Method

ABSTRACT

A wellbore plug isolation system and method for positioning plugs to isolate fracture zones in a horizontal, vertical, or deviated wellbore is disclosed. The system/method includes a wellbore casing laterally drilled into a hydrocarbon formation, a wellbore setting tool (WST) that sets a large inner diameter (ID) restriction sleeve member (RSM), and a restriction plug element (RPE). The RPE includes a first composition and a second composition that changes phase or strength under wellbore conditions. After a stage is perforated, RPEs are deployed to isolate toe ward pressure communication. The second composition changes phase to create flow channels in the RPE during production. In an alternate system/method, the second composition changes phase or strength thereby deforming the RPE to reduce size and pass through the RSM&#39;s. The RPEs are removed or left behind prior to initiating well production without the need for a milling procedure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part application of non-provisional patent application Ser. No. 14/459,042, entitled WELLBORE PLUG ISOLATION SYSTEM AND METHOD, filed Aug. 13, 2014.

PARTIAL WAIVER OF COPYRIGHT

All of the material in this patent application is subject to copyright protection under the copyright laws of the United States and of other countries. As of the first effective filing date of the present application, this material is protected as unpublished material.

However, permission to copy this material is hereby granted to the extent that the copyright owner has no objection to the facsimile reproduction by anyone of the patent documentation or patent disclosure, as it appears in the United States Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO A MICROFICHE APPENDIX

Not Applicable

FIELD OF THE INVENTION

The present invention generally relates to oil and gas extraction. Specifically, the invention attempts to isolate fracture zones through selectively positioning restriction elements within a wellbore casing. More specifically, it relates to restriction plug elements that are insoluble in well fluid but have properties such as phase or strength that vary with temperature so as to change shape to pass through restrictions during production.

PRIOR ART AND BACKGROUND OF THE INVENTION Prior Art Background

The process of extracting oil and gas typically consists of operations that include preparation, drilling, completion, production and abandonment.

Preparing a drilling site involves ensuring that it can be properly accessed and that the area where the rig and other equipment will be placed has been properly graded. Drilling pads and roads must be built and maintained which includes the spreading of stone on an impermeable liner to prevent impacts from any spills but also to allow any rain to drain properly.

In the drilling of oil and gas wells, a wellbore is formed using a drill bit that is urged downwardly at a lower end of a drill string. After drilling the wellbore is lined with a string of casing. An annular area is thus formed between the string of casing and the wellbore. A cementing operation is then conducted in order to fill the annular area with cement. The combination of cement and casing strengthens the wellbore and facilitates the isolation of certain areas of the formation behind the casing for the production of hydrocarbons.

The first step in completing a well is to create a connection between the final casing and the rock which is holding the oil and gas. There are various operations in which it may become necessary to isolate particular zones within the well. This is typically accomplished by temporarily plugging off the well casing at a given point or points with a plug.

A special tool, called a perforating gun, is lowered to the rock layer. This perforating gun is then fired, creating holes through the casing and the cement and into the targeted rock. These perforated holes connect the rock holding the oil and gas and the wellbore.

Since these perforations are only a few inches long and are performed more than a mile underground, no activity is detectable on the surface. The perforation gun is then removed before the next step, hydraulic fracturing stimulation fluid, which is a mixture of over 90% water and sand, plus a few chemical additives, is pumped under controlled conditions into deep, underground reservoir formations. The chemicals are used for lubrication and to keep bacteria from forming and to carry the sand. These chemicals are typically non-hazardous and range in concentrations from 0.1% to 0.5% by volume and are needed to help improve the performance and efficiency of the hydraulic fracturing. This stimulation fluid is pumped at high pressure out through the perforations made by the perforating gun. This process creates fractures in the shale rock which contains the oil and natural gas.

In many instances a single wellbore may traverse multiple hydrocarbon formations that are otherwise isolated from one another within the earth. It is also frequently desired to treat such hydrocarbon bearing formations with pressurized treatment fluids prior to producing from those formations. In order to ensure that a proper treatment is performed on a desired formation, that formation is typically isolated during treatment from other formations traversed by the wellbore. To achieve sequential treatment of multiple formations, the casing adjacent to the toe of a horizontal, vertical, or deviated wellbore is first perforated while the other portions of the casing are left unperforated. The perforated zone is then treated by pumping fluid under pressure into that zone through perforations. Following treatment a plug is placed adjacent to the perforated zone. The process is repeated until all the zones are perforated. The plugs are particularly useful in accomplishing operations such as isolating perforations in one portion of a well from perforations in another portion or for isolating the bottom of a well from a wellhead. The purpose of the plug is to isolate some portion of the well from another portion of the well.

Conventional prior art frac balls are typically made of a non-metallic material, such as reinforced epoxies and phenolics, that may be removed by milling in the event the balls become stuck. Such conventional prior art frac balls are made of materials that are designed to remain intact when exposed to hydraulic fracturing temperatures and pressures and are not significantly dissolved or degraded by the hydrocarbons or other media present within the well. When one of these prior art balls does not return to the surface and prevents lower balls from purging, coiled tubing must be lowered into the wellbore to mill the stuck ball and remove it from the seat. In addition, smaller-sized prior art balls that are not stuck in their seats still might not return to the surface because the pressure differential across the ball due to the uprising current in the large diameter casing might not be significant enough to overcome gravity. Consequently, while such smaller-sized balls may not completely block a zone, they are still likely to impede production by partially blocking the wellbore.

Subsequently, production of hydrocarbons from these zones requires that the sequentially set plugs be removed from the well. In order to reestablish flow past the existing plugs an operator must remove and/or destroy the plugs by milling, drilling, or dissolving the plugs.

Prior Art System Overview (0100)

As generally seen in the system diagram of FIG. 1 (0100), prior art systems associated with oil and gas extraction may include a wellbore casing (0120) laterally drilled into a wellbore. A plurality of frac plugs (0110, 0111, 0112, 0113) may be set to isolate multiple hydraulic fracturing zones (0101, 0102, 0103). Each frac plug is positioned to isolate a hydraulic fracturing zone from the rest of the unperforated zones. The positions of frac plugs may be defined by preset sleeves in the wellbore casing. For example, frac plug (0111) is positioned such that hydraulic fracturing zone (0101) is isolated from downstream (injection or toe end) hydraulic fracturing zones (0102, 0103). Subsequently, the hydraulic fracturing zone (0101) is perforated using a perforation gun and fractured. Preset plug/sleeve positions in the casing, precludes change of fracture zone locations after a wellbore casing has been installed. Therefore, there is a need to position a plug at a desired location after a wellbore casing has been installed without depending on a predefined sleeve location integral to the wellbore casing to position the plug.

Furthermore, after well completions, sleeves used to set frac plugs may have a smaller inner diameter constricting fluid flow when well production is initiated. Therefore, there is a need for a relatively large inner diameter sleeves after well completion that allow for unrestricted well production fluid flow.

Additionally, frac plugs can be inadvertently set at undesired locations in the wellbore casing creating unwanted constrictions. The constrictions may latch wellbore tools that are run for future operations and cause unwanted removal process. Therefore, there is a need to prevent premature set conditions caused by conventional frac plugs.

Exemplary prior art covering degrading frac plugs includes the following:

U.S. Pat. No. 8,714,268, Method of making and using multi-component disappearing tripping ball; A method for making a tripping ball comprising configuring two or more parts to collectively make up a portion of a tripping ball; and assembling the two or more parts by adhering the two or more parts together with an adherent dissolvable material to form the tripping ball, the adherent dissolvable material operatively arranged to dissolve for enabling the two or more parts to separate from each other;

U.S. Pat. No. 8,231,947, Oilfield elements having controlled solubility and methods of use; Oilfield elements are described, one embodiment comprising a combination of a normally insoluble metal with an element selected from a second metal, a semi-metallic material, and non-metallic materials; and one or more solubility-modified high strength and/or high-toughness polymeric materials selected from polyamides, polyethers, and liquid crystal polymers;

U.S. Pat. No. 8,567,494, Well operating elements comprising a soluble component and methods of use; comprising a first component that is substantially non-dissolvable when exposed to a selected wellbore environment and a second component that is soluble in the selected wellbore environment and whose rate and/or location of dissolution is at least partially controlled by structure of the first component; A second embodiment includes the component that is soluble in the selected wellbore environment, and one or more exposure holes or passages in the soluble component to control its solubility;

US 20120181032, Disintegrating ball for sealing frac plug seat; A composition for a ball that disintegrates, dissolves, delaminates or otherwise experiences a significant degradation of its physical properties over time in the presence of hydrocarbons and formation heat;

U.S. Pat. No. 8,657,018, Circulating sub; teaches erodible hollow balls in the fluid flow and more particularly is adapted to be eroded to a certain extent and then collapse or implode due to the pressure of the external fluid being far higher than the internal pressure of the ball;

The aforementioned prior art teach frac balls that degrade, unlink, dissolve, and erode in the presence of wellbore fluids. However, they do not teach any methodology by which frac balls change shape by melting, phase change, strength, or elasticity to address a wide variety of system applications, including but not limited to wellbore plug isolation.

Prior Art Method Overview (0200)

As generally seen in the method of FIG. 2 (0200), prior art associated with oil and gas extraction includes site preparation and installation of a wellbore casing (0120) (0201). Preset sleeves may be installed as an integral part of the wellbore casing (0120) to position frac plugs for isolation. After setting a frac plug and isolating a hydraulic fracturing zone in step (0202), a perforating gun is positioned in the isolated zone in step (0203). Subsequently, the perforating gun detonates and perforates the wellbore casing and the cement into the hydrocarbon formation. The perforating gun is next moved to an adjacent position for further perforation until the hydraulic fracturing zone is completely perforated. In step (0204), hydraulic fracturing fluid is pumped into the perforations at high pressures. The steps comprising of setting up a plug (0202), isolating a hydraulic fracturing zone, perforating the hydraulic fracturing zone (0203) and pumping hydraulic fracturing fluids into the perforations (0204), are repeated until all hydraulic fracturing zones in the wellbore casing are processed. In step (0205), if all hydraulic fracturing zones are processed, the plugs are milled out with a milling tool and the resulting debris is pumped out or removed from the wellbore casing (0206). In step (0207) hydrocarbons are produced by pumping out from the hydraulic fracturing stages.

The step (0206) requires that removal/milling equipment be run into the well on a conveyance string which may typically be wire line, coiled tubing or jointed pipe. The process of perforating and plug setting steps represent a separate “trip” into and out of the wellbore with the required equipment. Each trip is time consuming and expensive. In addition, the process of drilling and milling the plugs creates debris that needs to be removed in another operation. Therefore, there is a need for isolating multiple hydraulic fracturing zones without the need for a milling operation. Furthermore, there is a need for positioning restrictive plug elements that could be removed in a feasible, economic, and timely manner before producing gas.

Deficiencies in the Prior Art

The prior art as detailed above suffers from the following deficiencies:

-   -   Prior art systems do not provide for positioning a ball seat at         a desired location after a wellbore casing has been installed,         without depending on a predefined sleeve location integral to         the wellbore casing to position the plug.     -   Prior art systems do not provide for isolating multiple         hydraulic fracturing zones without the need for a milling         operation.     -   Prior art systems do not provide for positioning restrictive         elements that could be removed in a feasible, economic, and         timely manner.     -   Prior art systems do not provide for setting larger inner         diameter sleeves to allow unrestricted well production fluid         flow.     -   Prior art systems cause undesired premature preset conditions         preventing further wellbore operations.

While some of the prior art may teach some solutions to several of these problems, the core issue of isolating hydraulic fracturing zones without the need for a milling operation has not been addressed by prior art.

Deficiencies in the Prior Art for Restriction Plug Elements

While the use of degradable/dissolvable frac balls has been proven for many years, they have certain limitations. The prior art as detailed above suffers from the following deficiencies:

-   -   Prior art systems do not provide for restriction plug elements         (frac balls) comprising meltable eutectic alloys that change         phase due to wellbore temperature.     -   Prior art systems do not provide for restriction plug elements         (frac balls) comprising compositions that change strength due to         wellbore temperature.     -   Prior art systems do not provide for restriction plug elements         comprising meltable material that melts to create flow passages.     -   Prior art systems do not provide for restriction plug elements         held together by an un-bonded mechanical insert.     -   Prior art systems do not provide for restriction plug elements         with a cooling flow channel to keep the plug in solid state         before liquefying.     -   Prior art systems do not provide for restriction sleeve member         with a cooling flow channel to retain a restriction plug element         in solid state before liquefying in the presence of wellbore         fluids.     -   Prior art systems do not provide for restriction plug elements         with dual chambers comprising a meltable eutectic alloy in one         chamber that melts to deform and distort the plug element.     -   Prior art methods do not provide for effectively reducing         overall cycle time for stage fracturing.     -   Prior art systems do not provide for cost effective restriction         plug elements.     -   Prior art systems require an acidic environment to degrade frac         balls.     -   Prior art systems that use PGA frac balls erode or pit wellbore         casing.     -   Prior art methods have no control on the amount of exposure of         the frac balls to wellbore and frac fluids.

While some of the prior art may teach some solutions to several of these problems, the core issue of removing reduced size plugs after changing phase to pass through the restriction sleeve members (ball seats) without the need for milling operation has not been addressed by prior art.

OBJECTIVES OF THE INVENTION

Accordingly, the objectives of the present invention are (among others) to circumvent the deficiencies in the prior art and affect the following objectives:

-   -   Provide for positioning a ball seat at a desired location after         a wellbore casing has been installed, without depending on a         predefined sleeve location integral to the wellbore casing to         position the plug.     -   Provide for isolating multiple hydraulic fracturing zones         without the need for a milling operation.     -   Provide for positioning restrictive elements that could be         removed in a feasible, economic, and timely manner.     -   Provide for setting larger inner diameter sleeves to allow         unrestricted well production fluid flow.     -   Provide for eliminating undesired premature preset conditions         that prevent further wellbore operations.     -   Provide for restriction plug elements (frac balls) comprising         meltable eutectic alloys that change phase due to wellbore         temperature.     -   Provide for restriction plug elements (frac balls) comprising         meltable eutectic alloys that change strength due to wellbore         temperature.     -   Provide for restriction plug elements comprising meltable         material that melts to create flow passages or flow channels.     -   Provide for restriction plug elements held together by an         un-bonded mechanical insert.     -   Provide for restriction plug elements with a cooling flow         channel to keep the plug in solid state before liquefying.     -   Provide for restriction sleeve member with a cooling flow         channel to retain a restriction plug element in solid state         before liquefying in the presence of wellbore fluids.     -   Provide for restriction plug elements with dual chambers         comprising a meltable eutectic alloy in one chamber that melts         to deform and distort the plug element.     -   Provide for effectively reducing overall cycle time for stage         fracturing.     -   Provide for a cost effective restriction plug elements     -   Provide for restriction plug elements that do not require an         acidic environment to degrade frac balls.     -   Provide for restriction plug elements that do not erode or pit         wellbore casing.     -   Provide for controlling the amount of exposure of the frac balls         to wellbore and frac fluids.     -   Provide for restriction plug elements that are independent of         the composition of the wellbore fluids Ph or chemical reactivity

While these objectives should not be understood to limit the teachings of the present invention, in general these objectives are achieved in part or in whole by the disclosed invention that is discussed in the following sections. One skilled in the art will no doubt be able to select aspects of the present invention as disclosed to affect any combination of the objectives described above.

BRIEF SUMMARY OF THE INVENTION System Overview

The present invention in various embodiments addresses one or more of the above objectives in the following manner. The present invention provides a system to isolate fracture zones in a horizontal, vertical, or deviated wellbore without the need for a milling operation. The system includes a wellbore casing laterally drilled into a hydrocarbon formation, a setting tool that sets a large inner diameter (ID) restriction sleeve member (RSM), and a restriction plug element (RPE). A setting tool deployed on a wireline or coil tubing into the wellbore casing sets and seals the RSM at a desired wellbore location. The setting tool forms a conforming seating surface (CSS) in the RSM. The CSS is shaped to engage/receive RPE deployed into the wellbore casing. The engaged/seated RPE isolates toe ward and heel ward fluid communication of the RSM to create a fracture zone. The RPEs are removed or pumped out or left behind without the need for a milling operation. A large ID RSM diminishes flow constriction during oil production.

Method Overview

The present invention system may be utilized in the context of an overall gas extraction method, wherein the wellbore plug isolation system described previously is controlled by a method having the following steps:

-   -   (1) installing the wellbore casing;     -   (2) deploying the WST along with the RSM and a perforating gun         string assembly (GSA) to a desired wellbore location in the         wellbore casing;     -   (3) setting the RSM at the desired wellbore location with the         WST and forming a seal;     -   (4) perforating the hydrocarbon formation with the perforating         GSA;     -   (5) removing the WST and perforating GSA from the wellbore         casing;     -   (6) deploying the RPE into the wellbore casing to seat in the         RSM and creating a hydraulic fracturing stage;     -   (7) fracturing the stage with fracturing fluids;     -   (8) checking if all hydraulic fracturing stages in the wellbore         casing have been completed, if not so, proceeding to the step         (2);     -   (9) enabling fluid flow in production direction; and     -   (10) commencing oil and gas production from the hydraulic         fracturing stages.

Integration of this and other preferred exemplary embodiment methods in conjunction with a variety of preferred exemplary embodiment systems described herein in anticipation by the overall scope of the present invention.

Restriction Plug Element System Overview

The present invention in various embodiments addresses one or more of the above objectives in the following manner. The present invention provides a system to isolate fracture zones in a horizontal, vertical, or deviated wellbore without the need for a milling operation. The system includes a wellbore casing laterally drilled into a hydrocarbon formation, a wellbore setting tool (WST) that sets a large inner diameter (ID) restriction sleeve member (RSM), and a restriction plug element (RPE). The RPE includes a first composition and a second composition that changes phase or strength under wellbore conditions. After a stage is perforated, RPEs are deployed to isolate toe ward pressure communication. The second composition changes phase to create flow channels in the RPE during production. In an alternate system/method, the second composition changes phase or strength thereby deforming the RPE to reduce size and pass through the RSM's. The RPEs are removed or left behind prior to initiating well production without the need for a milling procedure.

Restriction Plug Element Method Overview

The present invention system may be utilized in the context of an overall gas extraction method, wherein the wellbore plug isolation system with a restriction plug element described previously is controlled by a method having the following steps:

-   -   (1) checking if a restriction sleeve member (RSM) is present, if         so, proceeding to step (3);     -   (2) setting a RSM at a wellbore location in a wellbore casing;     -   (3) perforating a hydrocarbon formation with a perforating gun         string assembly;     -   (4) deploying the RPE into the wellbore casing to isolate toe         end fluid communication and create a hydraulic fracturing stage;     -   (5) controlling the RPE contact temperature to maintain a phase         in the second composition;     -   (6) fracturing the fracturing stage with fracturing fluids;     -   (7) controlling the RPE contact temperature to enable the second         composition to undergo phase change;     -   (8) checking if all hydraulic fracturing stages in the wellbore         casing have been completed, if not so, repeating steps (1) to         (7); and     -   (9) enabling fluid flow in production direction.

Integration of this and other preferred exemplary embodiment methods in conjunction with a variety of preferred exemplary embodiment systems described herein in anticipation by the overall scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the advantages provided by the invention, reference should be made to the following detailed description together with the accompanying drawings wherein:

FIG. 1 illustrates a system block overview diagram describing how prior art systems use plugs to isolate hydraulic fracturing zones.

FIG. 2 illustrates a flowchart describing how prior art systems extract gas from hydrocarbon formations.

FIG. 3 illustrates an exemplary system side view of a spherical restriction plug element/restriction sleeve member overview depicting a presently preferred embodiment of the present invention.

FIG. 3 a illustrates an exemplary system side view of a spherical restriction plug element/restriction sleeve member overview depicting a presently preferred embodiment of the present invention.

FIG. 4 illustrates a side perspective view of a spherical restriction plug element/restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 5 illustrates an exemplary wellbore system overview depicting multiple stages of a preferred embodiment of the present invention.

FIG. 6 illustrates a detailed flowchart of a preferred exemplary wellbore plug isolation method used in some preferred exemplary invention embodiments.

FIG. 7 illustrates a side view of a cylindrical restriction plug element seated in a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 8 illustrates a side perspective view of a cylindrical restriction plug element seated in a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 9 illustrates a side view of a dart restriction plug element seated in a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 10 illustrates a side perspective view of a dart restriction plug element seated in a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 10 a illustrates a side perspective view of a dart restriction plug element depicting a preferred exemplary system embodiment.

FIG. 10 b illustrates another perspective view of a dart restriction plug element depicting a preferred exemplary system embodiment.

FIG. 11 illustrates a side view of a restriction sleeve member sealed with an elastomeric element depicting a preferred exemplary system embodiment.

FIG. 12 illustrates a side perspective view of a restriction sleeve member sealed with gripping/sealing element depicting a preferred exemplary system embodiment.

FIG. 13 illustrates side view of an inner profile of a restriction sleeve member sealed against an inner surface of a wellbore casing depicting a preferred exemplary system embodiment.

FIG. 14 illustrates a wellbore setting tool creating inner and outer profiles in the restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 15 illustrates a wellbore setting tool creating outer profiles in the restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 16 illustrates a detailed cross section view of a wellbore setting tool creating inner profiles in the restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 17 illustrates a detailed cross section view of a wellbore setting tool creating inner profiles and outer profiles in the restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 18 illustrates a cross section view of a wellbore setting tool setting a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 19 illustrates a detailed cross section view of a wellbore setting tool setting a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 20 illustrates a detailed side section view of a wellbore setting tool setting a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 21 illustrates a detailed perspective view of a wellbore setting tool setting a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 22 illustrates another detailed perspective view of a wellbore setting tool setting a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 23 illustrates a cross section view of a wellbore setting tool setting a restriction sleeve member and removing the tool depicting a preferred exemplary system embodiment.

FIG. 24 illustrates a detailed cross section view of wellbore setting tool setting a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 25 illustrates a cross section view of wellbore setting tool removed from wellbore casing depicting a preferred exemplary system embodiment.

FIG. 26 illustrates a cross section view of a spherical restriction plug element deployed and seated into a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 27 illustrates a detailed cross section view of a spherical restriction plug element deployed into a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 28 illustrates a detailed cross section view of a spherical restriction plug element seated in a restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 29 illustrates a cross section view of wellbore setting tool setting a restriction sleeve member seating a second restriction plug element depicting a preferred exemplary system embodiment.

FIG. 30 illustrates a detailed cross section view of a wellbore setting tool setting a second restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 31 illustrates a detailed cross section view of a spherical restriction plug element seated in a second restriction sleeve member depicting a preferred exemplary system embodiment.

FIG. 32 illustrates a cross section view of a restriction sleeve member with flow channels according to a preferred exemplary system embodiment.

FIG. 33 illustrates a detailed cross section view of a restriction sleeve member with flow channels according to a preferred exemplary system embodiment.

FIG. 34 illustrates a perspective view of a restriction sleeve member with flow channels according to a preferred exemplary system embodiment.

FIG. 35 illustrates a cross section view of a double set restriction sleeve member according to a preferred exemplary system embodiment.

FIG. 36 illustrates a detailed cross section view of a double set restriction sleeve member according to a preferred exemplary system embodiment.

FIG. 37 illustrates a perspective view of a double set restriction sleeve member according to a preferred exemplary system embodiment.

FIG. 38 illustrates a cross section view of a WST setting restriction sleeve member at single, double and triple locations according to a preferred exemplary system embodiment.

FIG. 39 illustrates a cross section view of a WST with triple set restriction sleeve member according to a preferred exemplary system embodiment.

FIG. 40 illustrates a detailed cross section view of a triple set restriction sleeve member according to a preferred exemplary system embodiment.

FIG. 41 illustrates a detailed perspective view of a triple set restriction sleeve member according to a preferred exemplary system embodiment.

FIG. 42 illustrates a cross section view of a restriction plug element with a first composition surrounding a hollow second composition according to a preferred exemplary system embodiment.

FIG. 43 illustrates a cross section view of a restriction plug element with a first composition surrounding a solid second composition according to a preferred exemplary system embodiment.

FIG. 44 illustrates a cross section view of a restriction plug element with a first composition surrounding a second composition with a passage way according to a preferred exemplary system embodiment.

FIG. 45 illustrates a perspective view of a restriction plug element with a first composition surrounding a second composition with a passage way according to a preferred exemplary system embodiment.

FIG. 46 a illustrates a cross section view of a restriction plug element with a first composition surrounding a second composition with a passage way and the restriction plug element positioned in a restriction sleeve member during production according to a preferred exemplary system embodiment.

FIG. 46 b illustrates a cross section view of a restriction plug element with a first composition surrounding a second composition with a passage way and the restriction plug element positioned in a restriction sleeve member during fracturing according to a preferred exemplary system embodiment.

FIG. 47 illustrates a cross section view of a restriction plug element with a second composition surrounding a solid first composition according to a preferred exemplary system embodiment.

FIG. 48 illustrates a cross section view of a restriction plug element with a second composition surrounding a hollow first composition according to a preferred exemplary system embodiment.

FIG. 49 illustrates a perspective view of a restriction plug element with a first composition with a passage way surrounding a second composition that surrounds a third composition according to a preferred exemplary system embodiment.

FIG. 50 illustrates a cross section view of a restriction plug element with a first composition surrounding a second composition in flow channels according to a preferred exemplary system embodiment.

FIG. 51 illustrates a perspective view of a restriction plug element with a first composition surrounding a second composition in flow channels according to a preferred exemplary system embodiment.

FIG. 52 illustrates a detailed flowchart of a preferred exemplary wellbore plug isolation method with a restriction plug element (RPE) used in some preferred exemplary invention embodiments.

FIG. 53 illustrates a spherical restriction plug element with a first composition mechanically held together by a toroid mechanical second composition according to a preferred exemplary system embodiment.

FIG. 54 illustrates a cross section view of a spherical restriction plug element with a first composition mechanically held together by a toroid mechanical second composition according to a preferred exemplary system embodiment.

FIG. 55 illustrates a top perspective view of a spherical restriction plug element with a first composition mechanically held together by a toroid mechanical second composition according to a preferred exemplary system embodiment.

FIG. 56 illustrates a side perspective view of a spherical restriction plug element with a first composition mechanically held together by a toroid mechanical second composition according to a preferred exemplary system embodiment.

FIG. 57 illustrates a front cross section view of a spherical restriction plug element with a first composition mechanically held together by a toroid mechanical second composition according to a preferred exemplary system embodiment.

FIG. 57 a illustrates an ovoid restriction plug element with a first composition mechanically held together by a toroid mechanical second composition according to a preferred exemplary system embodiment.

FIG. 58 illustrates a spherical restriction plug element with a first composition surrounding a second composition with a movable piston according to a preferred exemplary system embodiment.

FIG. 59 illustrates a perspective view of a spherical restriction plug element with a first composition surrounding a second composition with a movable piston according to a preferred exemplary system embodiment.

FIG. 60 illustrates a cross section view of a spherical restriction plug element with a first composition surrounding a second composition with a movable piston according to a preferred exemplary system embodiment.

FIG. 61 illustrates a perspective view of a sliding piston within a spherical restriction plug element according to a preferred exemplary system embodiment.

FIG. 62 illustrates a cross section view of a sliding piston within a spherical restriction plug element according to a preferred exemplary system embodiment.

FIG. 63 illustrates a cylindrical restriction plug element with external flow channels according to a preferred exemplary system embodiment.

FIG. 64 illustrates a cylindrical restriction plug element with internal flow channels according to a preferred exemplary system embodiment.

FIG. 65 illustrates a banded cylindrical restriction plug element according to a preferred exemplary system embodiment.

FIG. 66 illustrates an ovoid restriction plug element with external flow channels according to a preferred exemplary system embodiment.

FIG. 67 illustrates an ovoid restriction plug element with internal flow channels according to a preferred exemplary system embodiment.

FIG. 68 illustrates a banded ovoid restriction plug element according to a preferred exemplary system embodiment.

FIG. 69 illustrates a dart restriction plug element with external flow channels according to a preferred exemplary system embodiment.

FIG. 70 illustrates a dart restriction plug element with internal flow channels according to a preferred exemplary system embodiment.

FIG. 71 illustrates a banded dart restriction plug element according to a preferred exemplary system embodiment.

FIG. 72 illustrates a dart shaped restriction plug element with a first composition fins attached to a central second composition according to a preferred exemplary system embodiment.

FIG. 73 illustrates a dart shaped restriction plug element with a second composition fins attached to a central first composition according to a preferred exemplary system embodiment.

FIG. 74 shows a plot of temperature versus time in a wellbore.

DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detailed preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiment illustrated.

The numerous innovative teachings of the present application will be described with particular reference to the presently preferred embodiment, wherein these innovative teachings are advantageously applied to the particular problems of a wellbore plug isolation system and method. However, it should be understood that this embodiment is only one example of the many advantageous uses of the innovative teachings herein. In general, statements made in the specification of the present application do not necessarily limit any of the various claimed inventions. Moreover, some statements may apply to some inventive features but not to others.

GLOSSARY OF TERMS

-   -   RSM: Restriction Sleeve Member, a cylindrical member positioned         at a selected wellbore location.     -   RPE: Restriction Plug Element, an element configured to isolate         and block fluid communication.     -   CSS: Conforming Seating Surface, a seat formed within RSM.     -   ICD: Inner Casing Diameter, inner diameter of a wellbore casing.     -   ICS: Inner Casing Surface, inner surface of a wellbore casing.     -   ISD: Inner Sleeve Diameter, inner diameter of a RSM.     -   ISS: Inner Sleeve Surface, inner surface of a RSM.     -   WST: Wellbore Setting Tool, a tool that functions to set and         seal RSMs.     -   GSA: Gun String Assembly, a cascaded string of perforating guns         coupled to each other.

Preferred Embodiment System Block Diagram (0300, 0400)

The present invention may be seen in more detail as generally illustrated in FIG. 3 (0300) and FIG. 3 a (0320), wherein a wellbore casing (0304) is installed inside a hydrocarbon formation (0302) and held in place by wellbore cement (0301). The wellbore casing (0304) may have an inside casing surface (ICS) associated with an inside casing diameter (ICD) (0308). For example, ICD (0308) may range from 2¾ inch to 12 inches. A restriction sleeve member (RSM) (0303) that fits inside of the wellbore casing is disposed therein by a wellbore setting tool (WST) to seal against the inside surface of the wellbore casing. The seal may be leaky or tight depending on the setting of RSM (0303). The RSM (0303) may be a hollow cylindrical member having an inner sleeve surface and an outer sleeve surface. The RSM (0303) may be concentric with the wellbore casing and coaxially fit within the ICS. In one preferred exemplary embodiment, the seal prevents RSM (0303) from substantial axially or longitudinally sliding along the inside surface of the wellbore casing. The RSM (0303) may be associated with an inner sleeve diameter (ISD) (0307) that is configured to fit within ICD (0308) of the wellbore casing (0304). In another preferred exemplary embodiment, ISD (0307) is large enough to enable unrestricted fluid movement through inside sleeve surface (ISS) during production. The ratio of ISD (0307) to ICD (0308) may range from 0.5 to 0.99. For example, ICD may be 4.8 inches and ISD may be 4.1 inches. In the foregoing example, the ratio of ISD (0307) and ICD (0308) is 0.85. The diameter of ISD (0307) may further degrade during production from wellbore fluids enabling fluid flow on almost the original diameter of the well casing. In a further preferred exemplary embodiment, RSM (0303) may be made from a material comprising of aluminum, iron, steel, titanium, tungsten, copper, bronze, brass, plastic, composite, natural fiber, and carbide. The RSM (0303) may be made of degradable material or a commercially available material.

In a preferred exemplary embodiment, the WST may set RSM (0303) to the ICS in compression mode to form an inner profile on the RSM (0303). The inner profile could form a tight or leaky seal preventing substantial axial movement of the RSM (0303). In another preferred exemplary embodiment, the WST may set RSM (0303) to the ICS in expansion mode providing more contact surface for sealing RSM (0303) against ICS. Further details of setting RSM (0303) through compression and expansion modes are further described below in FIG. 15.

In another preferred exemplary embodiment, the WST may set RSM (0303) using a gripping/sealing element disposed of therein with RSM (0303) to grip the outside surface of RSM (0303) to ICS. Further details of setting RSM (0303) through compression and expansion modes are described below in FIG. 11 (1100).

In another preferred exemplary embodiment, the WST may set RSM (0303) at any desired location within wellbore casing (0304). The desired location may be selected based on information such as the preferred hydrocarbon formation area, fraction stage, and wellbore conditions. The desired location may be chosen to create uneven hydraulic fracturing stages. For example, a shorter hydraulic fracturing stage may comprise a single perforating position so that the RSM locations are selected close to each other to accommodate the perforating position. Similarly, a longer hydraulic fracturing stage may comprise multiple perforating positions so that the RSM locations are selected as far to each other to accommodate the multiple perforating positions. Shorter and longer hydraulic fracturing positions may be determined based on the specific information of hydrocarbon formation (0302). A mudlog analyzes the mud during drilling operations for hydrocarbon information at locations in the wellbore. Prevailing mudlog conditions may be monitored to dynamically change the desired location of RSM (0303).

The WST may create a conforming seating surface (CSS) (0306) within RSM (0303). The WST may form a beveled edge on the production end (heel end) of the RSM (0303) by constricting the inner diameter region of RSM (0303) to create the CSS (0306). The inner surface of the CSS (0306) could be formed such that it seats and retains a restriction plug element (RPE) (0305). The diameter of the RPE (0305) is chosen such that it is less than the outer diameter and greater than the inner diameter of RSM (0303). The CSS (0306) and RPE (0305) may be complementary shaped such that RPE (0305) seats against CSS (0306). For example, RPE (0306) may be spherically shaped and the CSS (0306) may be beveled shaped to enable RPE (0305) to seat in CSS (0306) when a differential pressure is applied. The RPE (0305) may pressure lock against CSS (0306) when differential pressure is applied i.e., when the pressure upstream (production or heel end) of the RSM (0303) location is greater than the pressure downstream (injection or toe end) of the RSM (0303). The differential pressure established across the RSM (0303) locks RPE (0305) in place isolating downstream (injection or toe end) fluid communication. According to one preferred exemplary embodiment, RPE (0305) seated in CSS (0306) isolates a zone to enable hydraulic fracturing operations to be performed in the zone without affecting downstream (injection or toe end) hydraulic fracturing stages. The RPE (0305) may also be configured in other shapes such as a plug, dart or a cylinder. It should be noted that one skilled in the art would appreciate that any other shapes conforming to the seating surface may be used for RPEs to achieve similar isolation affect as described above.

According to another preferred exemplary embodiment, RPE (0305) may seat directly in RSM (0303) without the need for a CSS (0306). In this context, RPE (0305) may lock against the vertical edges of the RSM (0303) which may necessitate a larger diameter RPE (0305).

According to yet another preferred exemplary embodiment, RPE (0305) may degrade over time in the well fluids eliminating the need to be removed before production. The RPE (0305) degradation may also be accelerated by acidic components of hydraulic fracturing fluids or wellbore fluids, thereby reducing the diameter of RPE (0305) enabling it to flow out (pumped out) of the wellbore casing or flow back (pumped back) to the surface before production phase commences.

In another preferred exemplary embodiment, RPE (0305) may be made of a metallic material, non-metallic material, a carbide material, or any other commercially available material.

Preferred Embodiment Multistage System Diagram (0500)

The present invention may be seen in more detail as generally illustrated in FIG. 5 (0500), wherein a wellbore casing (0504) is shown after hydraulic fracturing is performed in multiple stages (fracture intervals) according to a method described herewith below in FIG. 6 (0600). A plurality of stages (0520, 0521, 0522, 0523) are created by setting RSMs (0511, 0512, 0513) at desired positions followed by isolating each stage successively with restriction plug elements RPEs (0501, 0502, 0503). A RSM (0513) may be set by a WST followed by positioning a perforating gun string assembly (GSA) in hydraulic fracturing zone (0522) and perforating the interval. Subsequently, RPE (0503) is deployed and the stage (0522) is hydraulically fractured. The WST and the perforating GSA are removed for further operations. Thereafter, RSM (0512) is set and sealed by WST followed by a perforation operation. Another RPE (0502) is deployed to seat in RSM (0512) to form hydraulic fracturing zone (0521). Thereafter the stage (0521) is hydraulically fracturing. Similarly, hydraulic fracturing zone (0520) is created and hydraulically fractured.

According to one aspect of a preferred exemplary embodiment, RSMs may be set by WST at desired locations to enable RPEs to create multiple hydraulic fracturing zones in the wellbore casing. The hydraulic fracturing zones may be equally spaced or unevenly spaced depending on wellbore conditions or hydrocarbon formation locations.

According to another preferred exemplary embodiment, RPEs are locked in place due to pressure differential established across RSMs. For example, RPE (0502) is locked in the seat of RSM (0512) due to a positive pressure differential established across RSM (0512) i.e., pressure upstream (hydraulic fracturing stages 0520, 0521 and stages towards heel of the wellbore casing) is greater than pressure downstream (hydraulic fracturing stages 0522, 0523 and stages towards toe of the wellbore casing).

According a further preferred exemplary embodiment, RPEs (0501, 0502, 0503) may degrade over time, flowed back by pumping, or flowed into the wellbore, after completion of all stages in the wellbore, eliminating the need for additional milling operations.

According a further preferred exemplary embodiment the RPE's may change shape or strength such that they may pass through a RSM in either the production (heel end) or injection direction (toe end). For example RPE (0512) may degrade and change shape such it may pass through RSM (0511) in the production direction or RSM (0513) in the injection direction. The RPEs may also be degraded such that they are in between the RSMs of current stage and a previous stage restricting fluid communication towards the injection end (toe end) but enabling fluid flow in the production direction (heel end). For example, RPE (0502) may degrade such it is seated against the injection end (toe end) of RSM (0511) that may have flow channels. Flow channels in the RSM are further described below in FIG. 32 (3200) and FIG. 34 (3400).

According to yet another preferred exemplary embodiment, inner diameters of RSMs (0511, 0512, 0513) may be the same and large enough to allow unrestricted fluid flow during well production operations. The RSMs (0511, 0512, 0513) may further degrade in well fluids to provide an even larger diameter comparable to the inner diameter of the well casing (0504) allowing enhanced fluid flow during well production. The degradation could be accelerated by acids in the hydraulic fracturing fluids.

Preferred Exemplary Restriction Plug Elements (RPE)

It should be noted that some of the material and designs of the RPE described below may not be limited and should not be construed as a limitation. This basic RPE design and materials may be augmented with a variety of ancillary embodiments, including but not limited to:

-   -   Made of multi layered materials, where at least one layer of the         material melts or deforms at temperature allowing the size or         shape to change.     -   May be a solid core with an outer layer of meltable material.     -   May or may not have another outer layer, such as a rubber         coating.     -   May be a single material, non-degradable.     -   Outer layer may or may not have holes in it, such that an inner         layer could melt and liquid may escape.     -   Passage ways through them which are filled with meltable,         degradable, or dissolving materials.     -   Use of downhole temperature and pressure, which change during         the stimulation and subsequent well warm up to change the shape         of barriers with laminated multilayered materials.     -   Use of a solid core that is degradable or erodible.     -   Use of acid soluble alloy balls.     -   Use of water dissolvable polymer frac balls.     -   Use of poly glycolic acid balls.

Preferred Exemplary Wellbore Plug Isolation Flowchart Embodiment (0600)

As generally seen in the flow chart of FIG. 6 (0600), a preferred exemplary wellbore plug isolation method may be generally described in terms of the following steps:

-   -   (1) installing the wellbore casing (0601);     -   (2) deploying the WST along with the RSM to a desired wellbore         location in the wellbore casing along with a perforating gun         string assembly (GSA); the WST could be deployed by wireline,         coil tube, or tubing-conveyed perforating (TCP) (0602); the         perforating GSA may comprise plural perforating guns;     -   (3) setting the RSM at the desired wellbore location with the         WST; the WST could set RSM with a power charge or pressure         (0603); The power charge generates pressure inside the setting         tool that sets the RSM; the RSM may or may not have a conforming         seating surface (CSS); the CSS may be machined or formed by the         WST at the desired wellbore location;     -   (4) perforating hydrocarbon formation with the perforating GSA;         the perforating GSA may perforate one interval at a time         followed by pulling the GSA and perforating the next interval in         the stage; the perforation operation is continued until all the         intervals in the stage are completed;     -   (5) removing the WST and the perforating GSA from the wellbore         casing; the WST could be removed by wireline, coil tube, or TCP         (0605);     -   (6) deploying the RPE to seat in the RSM isolating fluid         communication between upstream (heel or production end) of the         RSM and downstream (toe or injection end) of the RSM and         creating a hydraulic fracturing stage; RPE may be pumped from         the surface, deployed by gravity, or set by a tool; If a CSS is         present in the RSM, the RPE may be seated in the CSS; RPE and         CSS complementary shapes enable RPE to seat into the CSS;         positive differential pressure may enable RPE to be driven and         locked into the CSS (0606);     -   (7) fracturing the hydraulic fracturing stage; by pumping         hydraulic fracturing fluid at high pressure to create pathways         in hydrocarbon formations (0607);     -   (8) checking if all hydraulic fracturing stages in the wellbore         casing have been completed, if not so, proceeding to step         (0602); prepare to deploy the WST to a different wellbore         location towards the heel end of the already fractured stage;         hydraulic fracturing stages may be determined by the length of         the casing installed in the hydrocarbon formation; if all stages         have been fractured proceed to step (0609), (0608);     -   (9) enabling fluid flow in the production (heel end) direction;         fluid flow may been enabled through flow channels designed in         the RSM while the RPEs are positioned in between the RSMs; fluid         flow may also be been enabled through flow channels designed in         the RPEs and RSMs; alternatively RPEs may also be removed from         the wellbore casing or the RPEs could be flowed back to surface,         pumped into the wellbore, or degraded in the presence of         wellbore fluids or acid (0609); and     -   (10) commencing oil and gas production from all the         hydraulically fractured stages (0610).

Preferred Embodiment Side View Cylindrical Restriction Plug System Block Diagram (0700, 0800)

One preferred embodiment may be seen in more detail as generally illustrated in FIG. 7 (0700) and FIG. 8 (0800), wherein a cylindrical restrictive plug element (0702) is seated in CSS (0704) to provide downstream pressure isolation. A wellbore casing (0701) is installed in a hydrocarbon formation. A wellbore setting tool may set RSM (0703) at a desired location and seal it against the inside surface of the wellbore casing (0701). The WST may form a CSS (0704) in the RSM (0703) as described by foregoing method described in FIG. 6 (0600). According to one preferred exemplary embodiment, a cylindrical shaped restrictive plug element (RPE) (0702) may be deployed into the wellbore casing to seat in CSS (0704).

The diameter of the RPE (0702) is chosen such that it is less than the outer diameter and greater than the inner diameter of RSM (0703). The CSS (0704) and RPE (0702) may be complementary shaped such that RPE (0702) seats against CSS (0704). For example, RPE (0702) may be cylindrically shaped and CSS (0704) may be beveled shaped to enable RPE (0702) to seat in CSS (0704) when a differential pressure is applied. The RPE (0702) may pressure lock against CSS (0704) when differential pressure is applied.

It should be noted that, if a CSS is not present in the RSM (0703) or not formed by the WST, the cylindrical RPE (0702) may directly seat against the edges of the RSM (0703).

Preferred Embodiment Side View Dart Restriction Plug System Block Diagram (0900-1020)

Yet another preferred embodiment may be seen in more detail as generally illustrated in FIG. 9 (0900), FIG. 10 (1000), FIG. 10 a (1010), and FIG. 10 b (1020) wherein a dart shaped restrictive plug element (0902) is seated in CSS (0904) to provide pressure isolation. According to a similar process described above in FIG. 7, RPE (0902) is used to isolate and create fracture zones to enable perforation and hydraulic fracturing operations in the fracture zones. As shown in the perspective views of the dart RPE in FIG. 10 a (1010) and FIG. 10 b (1020), the dart RPE is complementarily shaped to be seated in the RSM. The dart RPE (0902) is designed such that the fingers of the RPE (0902) are compressed during production enabling fluid flow in the production direction.

Preferred Embodiment Side Cross Section View of a Restriction Sleeve Member System Block Diagram (1100, 1200)

One preferred embodiment may be seen in more detail as generally illustrated in FIG. 11 (1100) and FIG. 12 (1200), wherein a restrictive sleeve member RSM (1104) is sealed against the inner surface of a wellbore casing (1101) with a plurality of gripping/sealing elements (1103). Gripping elements may be elastomers, carbide buttons, or wicker forms. After a wellbore casing (1101) is installed, a wellbore setting tool may be deployed along with RSM (1104) to a desired wellbore location. The WST may then compress the RSM (1104) to form plural inner profiles (1105) on the inside surface of the RSM (1104) at the desired location. In one preferred exemplary embodiment, the inner profiles (1105) may be formed prior to deploying to the desired wellbore location. The compressive stress component in the inner profiles (1104) may aid in sealing the RSM (1104) to the inner surface of a wellbore casing (1101). A plurality of gripping/sealing elements (1103) may be used to further strengthen the seal (1106) to prevent substantial axial or longitudinal movement of RSM (1104). The gripping elements (1103) may be an elastomer, carbide buttons, or wicker forms that can tightly grip against the inner surface of the wellbore casing (1101). The seal (1106) may be formed by plural inner profiles (1104), plural gripping elements (1103), or a combination of inner profiles (1104) and gripping elements (1103). Subsequently, the WST may form a CSS (1106) and seat a RPE (1102) to create downstream isolation (toe end) as described by the foregoing method in FIG. 6 (0600).

Preferred Embodiment Side Cross Section View of Inner and Outer Profiles of a Restriction Sleeve Member System Block Diagram (1300-1700)

Yet another preferred embodiment may be seen in more detail as generally illustrated in FIG. 13 (1300), wherein a restrictive sleeve member RSM (1304) is sealed against the inner surface of a wellbore casing (1301). After a wellbore casing (1301) is installed, a wellbore setting tool may be deployed along with RSM (1304) to a desired wellbore location. The WST may then compress the RSM (1304) to form plural inner profiles (1305) on the inside surface of the RSM (1304) and plural outer profiles (1303) on the outside surface of the RSM (1304) at the desired location. In one preferred exemplary embodiment, the inner profiles (1305) and outer profiles (1303) may be formed prior to deploying to the desired wellbore location. The compressive stress component in the inner profiles (1304) and outer profiles (1303) may aid in sealing the RSM (1304) to the inner surface of a wellbore casing (1301). The outer profiles (1303) may directly contact the inner surface of the wellbore casing at plural points of the protruded profiles to provide a seal (1306) and prevent axial or longitudinal movement of the RSM (1304).

Similarly, FIG. 15 (1500) illustrates a wireline setting tool creating inner and outer profiles in restriction sleeve members for sealing against the inner surface of the wellbore casing. FIG. 16 illustrates a detailed cross section view of a WST (1603) that forms an inner profile (1604) in a RSM (1602) to form a seal (1605) against the inner surface of wellbore casing (1601). Likewise, FIG. 17 (1700) illustrates a detailed cross section view of a WST (1703) that forms an inner profile (1704) and an outer profile (1706) in a RSM (1702) to form a seal (1705) against the inner surface of wellbore casing (1701). According to a preferred exemplary embodiment, inner and outer profiles in a RSM forms a seal against an inner surface of the wellbore casing preventing substantial axial and longitudinal movement of the RSM during perforation and hydraulic fracturing process.

Preferred Embodiment Wellbore Setting Tool (WST) System Block Diagram (1800-2200)

FIG. 18 (1800) and FIG. 19 (1900) show a front cross section view of a WST. According to a preferred exemplary embodiment, a wellbore setting tool (WST) may be seen in more detail as generally illustrated in FIG. 20 (2000). A WST-RSM sleeve adapter (2001) holds the RSM (2008) in place until it reaches the desired location down hole. After the RSM (2008) is at the desired location the WST-RSM sleeve adapter (2001) facilitates a reactionary force to engage the RSM (2008). When the WST (2002) is actuated, a RSM swaging member and plug seat (2005) provides the axial force to swage an expanding sleeve (2004) outward. A RSM-ICD expanding sleeve (2004) hoops outward to create a sealing surface between the RSM (2008) and inner casing diameter (ICD) (2009). After the WST (2002) actuation is complete, it may hold the RSM (2008) to the ICD (2009) by means of sealing force and potential use of other traction adding devices such as carbide buttons or wicker forms. The WST-RSM piston (2006) transmits the actuation force from the WST (2002) to the RSM (2008) by means of a shear set, which may be in the form of a machined ring or shear pins. The connecting rod (2003) holds the entire assembly together during the setting process. During activation, the connecting rod (2003) may transmit the setting force from the WST (2002) to the WST piston (2006). FIG. 21 (2100) and FIG. 22 (2200) show perspective views of the WST (2002) in more detail.

Preferred Embodiment Wellbore Plug Isolation System Block Diagram (2300-3100)

As generally seen in the aforementioned flow chart of FIG. 6 (0600), the steps implemented for wellbore plug isolation are illustrated in FIG. 23 (2300)-FIG. 31 (3100).

As described above in steps (0601), (0602), and (0603) FIG. 23 (2300) shows a wellbore setting tool (WST) (2301) setting a restriction sleeve member (2303) on the inside surface of a wellbore casing (2302). The WST (2301) may create a conforming seating surface (CSS) in the RSM (2303) or the CSS may be pre-machined. A wireline (2304) or TCP may be used to pump WST (2301) to a desired location in the wellbore casing (2302). FIG. 24 (2400) shows a detailed view of setting the RSM (2303) at a desired location.

FIG. 25 (2500) illustrates the stage perforated with perforating guns after setting the RSM (2303) and removing WST (2301) as aforementioned in steps (0604) and (0605).

FIG. 26 (2600) illustrates a restriction plug element (RPE) (2601) deployed into the wellbore casing as described in step (0606). The RPE (2601) may seat in the conforming seating surface in RSM (2303) or directly in the RSM if the CSS is not present. After the RPE (2601) is seated, the stage is isolated from toe end pressure communication. The isolated stage is hydraulically fractured as described in step (0607). FIG. 27 (2700) shows details of RPE (2601) deployed into the wellbore casing. FIG. 28 (2800) shows details of RPE (2601) seated in RSM (2303).

FIG. 29 (2900) illustrates a WST (2301) setting another RSM (2903) at another desired location towards heel of the RSM (2303). Another RPE (2901) is deployed to seat in the RSM (2903). The RPE (2901) isolates another stage toe ward of the aforementioned isolated stage. The isolated stage is fractured with hydraulic fracturing fluids. FIG. 30 (3000) shows a detailed cross section view of WST (2301) setting RSM (2903) at a desired location. FIG. 31 (3100) shows a detailed cross section view of an RPE (2901) seated in RSM (2903). When all the stages are complete as described in (0608) the RPEs may remain in between the RSMs or flowed back or pumped into the wellbore (0609). According to a preferred exemplary embodiment, the RPE's and RSM's are degradable which enables larger inner diameter to efficiently pump oil and gas without restrictions and obstructions.

Preferred Embodiment Restriction Sleeve Member (RSM) With Flow Channels Block Diagram (3200-3400)

A further preferred embodiment may be seen in more detail as generally illustrated in FIG. 32 (3200), FIG. 33 (3300) and FIG. 34 (3400), wherein a restrictive sleeve member RSM (3306) comprising flow channels (3301) is set inside a wellbore casing (3305). A conforming seating surface (CSS) (3303) may be formed in the RSM (3306). The flow channels (3301) are designed in RSM (3306) to enable fluid flow during oil and gas production. The flow channels provide a fluid path in the production direction when restriction plug elements (RPE) degrade but are not removed after all stages are hydraulically fractured as aforementioned in FIG. 0600) step (0609). The channels (3301) are designed such that there is unrestricted fluid flow in the production direction (heel ward) while the RPEs block fluid communication in the injection direction (toe ward). Leaving the RPEs in place provides a distinct advantage over the prior art where a milling operation is required to mill out frac plugs that are positioned to isolate stages.

According to yet another preferred embodiment, the RSMs may be designed with fingers on either end to facilitate milling operation, if needed. Toe end fingers (3302) and heel end fingers (3304) may be designed on the toe end and heel end the RSM (3306) respectively. In the context of a milling operation, the toe end fingers may be pushed towards the heel end fingers of the next RSM (toe ward) such that the fingers are intertwined and interlocked. Subsequently, all the RSMs may be interlocked with each other finally eventually mill out in one operation as compared to the current method of milling each RSM separately.

Preferred Embodiment Wellbore Setting Tool (WST) System Double Set Block Diagram (3500-3700)

As generally illustrated in FIG. 35 (3500), FIG. 36 (3600) and FIG. 37 (3700) a wellbore setting tool sets or seals on both sides of a restriction sleeve member (RSM) (3601) on the inner surface (3604) of a wellbore casing. In this context the WST swags the RSM on both sides (double set) and sets it to the inside surface of the wellbore casing. On one end of the RSM (3601), a RSM-ICD expanding sleeve in the WST may hoop outward to create a sealing surface between the RSM (3601) and inner casing diameter (ICS) (3604). On the other side of the RSM (3601), when WST actuation is complete, the WST may hold the RSM (3601) to the ICS (3604) by means of sealing force and potential use of other traction adding gripping devices (3603) such as elastomers, carbide buttons or wicker forms.

According to a preferred exemplary embodiment, a double set option is provided with a WST to seal one end of the RSM directly to the inner surface of the wellbore casing while the other end is sealed with a gripping element to prevent substantial axial and longitudinal movement.

Preferred Embodiment Wellbore Setting Tool (WST) System Multiple Set Block Diagram (3800-4100)

As generally illustrated in FIG. 38 (3800), FIG. 39 (3900), FIG. 40 (4000), and FIG. 41 (4100) a wellbore setting tool sets or seals RSM at multiple locations. FIG. 38 (3800) shows a WST (3810) that may set or seal RSM at single location (single set), a WST (3820) that may set or seal RSM at double locations (double set), or a WST (3830) that may set or seal RSM 3 locations (triple set). A more detail illustration of WST (3830) may be seen in FIG. 40 (4000). The WST (3830) sets RSM (4004) at 3 locations (4001), (4002), and (4003). According to a preferred exemplary embodiment, WST sets or seals RSM at multiple locations to prevent substantial axial or longitudinal movement of the RSM. It should be noted that single, double and triple sets have been shown for illustrations purposes only and should not be construed as a limitation. The WST could set or seal RSM at multiple locations and not limited to single, double, or triple set as aforementioned. An isometric view of the triple set can be seen in FIG. 41 (4100).

Preferred Embodiment Restriction Sleeve Member Polished Bore Receptacle (PBR)

According to a preferred exemplary embodiment, the restricted sleeve member could still be configured with or without a CSS. The inner sleeve surface (ISS) of the RSM may be made of a polished bore receptacle (PBR). Instead of an independently pumped down RPE, however, a sealing device could be deployed on a wireline or as part of a tubular string. The sealing device could then seal with sealing elements within the restricted diameter of the internal sleeve surface (ISS), but not in the ICS surface. PBR surface within the ISS provides a distinct advantage of selectively sealing RSM at desired wellbore locations to perform treatment or re-treatment operations between the sealed locations, well production test, or test for casing integrity.

Preferred Embodiment Restriction Plug Element First Composition Materials

The RPEs of the present invention are designed for strength, rigidity and hardness sufficient to withstand the high pressure differentials required during well stimulation, which typically range from about 1,000 pounds per square inch (psi) to about 10,000 psi. According to certain embodiments, the RPE of the present invention is formed of a material or combination of materials having sufficient strength, rigidity and hardness at a temperature of from about 150° F. to about 350° F., from about 150° F. to about 220° F. or from about 150° F. to about 200° F. to seat in the RSM and then withstand deformation under the high pressure ranging from about 1,000 psi to about 10,000 psi associated with hydraulic fracturing processes. The materials selected for first composition deform enough to allow a second composition to exit through a passage when the second composition changes phase or loses strength upon exposure to wellbore temperature or fracturing fluids.

One class of useful materials for the first composition is elastomers. “Elastomer” as used herein is a generic term for substances emulating natural rubber in that they stretch under tension, have a high tensile strength, retract rapidly, and substantially recover their original dimensions. The term includes natural and man-made elastomers, and the elastomer may be a thermoplastic elastomer or a non-thermoplastic elastomer. The term includes blends (physical mixtures) of elastomers, as well as copolymers, terpolymers, and multi-polymers. Useful elastomers may also include one or more additives, fillers, plasticizers, and the like. Other materials may non-degradable group that includes G-10 (glass reinforced Epoxy Laminate), FR4, PEEK (Injection Molded), Nylon GF, Torlon, Steel, Aluminum, Stainless Steel, Nylon MF, Nylon GF, Magnesium Alloy (without HCL), Ceramic, Cast Iron, Thermoset Plastics, and Elastomers (rubber, nitrile, niton, silicone, etc.). The first composition may also include materials from a long term degradable group that includes PGA (polyglycolic acid) and Magnesium Alloy (with HCL).

Preferred Embodiment Restriction Plug Element Second Composition Materials

According to a preferred exemplary embodiment, the second composition may change phase, when exposed to the wellbore temperature conditions, in a controlled fashion. The second composition may comprise a solid, a liquid, or a gas. The second composition may melt to change phase from solid to liquid, may change phase from solid to gas, or may vaporize to change phase from liquid to gas. The second composition may also be selected from materials that change a physical property such as strength or elasticity upon exposure to wellbore fluids or fracturing fluids. Table 2.0 as generally illustrated below, shows a yield temperature for individual alloy that change strength above the yield temperature. The alloys in Table 2.0 are a combination of weight percentages as shown in individual columns. The first composition may control the rate of phase change in the second composition. The second composition in the RPE may be tailored to the temperature profile of the wellbore conditions. The second composition may comprise a eutectic alloy, a metal, a non-metal, and combinations thereof. Eutectic alloys have two or more materials and have a eutectic composition. When a well-mixed, eutectic alloy melts (changes phase), it does so at a single, sharp temperature. The eutectic alloys may be selected from the list shown in Table 1.0. As generally shown in Table 1.0, the eutectic alloys may have a melting point (The temperature at which a solid changes state from solid to liquid at atmospheric pressure) range from 150° F. to 350° F. Eutectic or Non-Eutectic metals with designed melting points may be combinations of Bismuth, Lead, Tin, Cadmium, Thallium, Gallium, Antimony, also fusible alloys as shown below in Table 1.0 and Table 2.0.

Thermoplastics with low melting points such as Acrylic, Nylon, Polybenzimidazole, Polyethylene, Polypropylene, Polystyrene, Polyvinyl Chloride, Teflon may also function as a second composition material that change phase or change physical property such as strength or elasticity. These thermoplastics, when reinforced with glass or carbon fiber may initially create stronger materials that change physical property such as strength or elasticity upon exposure to temperatures in the wellbore or fracturing fluids.

TABLE 1.0 (Alloys Composition in weight %) Alloy Melting point Eutectic Bi Pb Sn In Cd Tl Ga Sb Rose's metal 98° C. no 50 25 25 — — — — — (208° F.) Cerrosafe 74° C. no 42.5 37.7 11.3 — 8.5 — — — (165° F.) Wood's metal 70° C. yes 50 26.7 13.3 — 10   — — — (158° F.) Field's metal 62° C. yes 32.5 — 16.5 51 — — — — (144° F.) Cerrolow 136 58° C. yes 49 18 12 21 — — — — (136° F.) Cerrolow 117 47.2° C. yes 44.7 22.6 8.3 19.1 5.3 — — — (117° F.) Bi—Pb—Sn—Cd—In—Tl 41.5° C. yes 40.3 22.2 10.7 17.7 8.1 0.01 — — (107° F.) Galinstan −19° C. yes <1.5 — 9.5-10.5 21-22 — — 68-69 <1.5 (−2° F.)

TABLE 2.0 (Alloys Composition in weight %) Melting Yield CS Alloys Range Temperature Name Bi Pb Sn Cd In (F.) (F.) Low 117 44.7 22.6 8.3 5.3 19.1 117-117 117 Low 136 49 18 12 21 136-136 136 Low 140 47.5 25.4 12.6 9.5 5 134-144 140 Low 147 48 25.63 12.77 9.6 4 142-149 147 Bend 158 50 26.7 13.3 10   — 158-158 158 Safe 165 42.5 37.7 11.3 8.5 — 160-190 165 Low 174 57 — 17 — 26 174-174 174 Shield 203 52.5 32 15.5 — — 203-203 203 Base 255 55.5 44.5 — — — 255-255 255 Tru 281 58 — 42 — — 281-281 281 Cast 302 40 — 60 — — 281-338 302

Materials which transform from solid to gas (sublimation), or are solid only at high pressures and low temperatures may also be selected as shown below in Table 3.0. For example, balls of Dry Ice (Solid Carbon Dioxide) would need to be kept at temperature below the specified melting point prior to use as a second composition material.

TABLE 3.0 Melting Composition in Weight % Point Eutectic Cs 73.71, K 22.14, Na 4.14[2] −78.2 yes Hg 91.5, Tl 8.5 −58 yes Hg 100 −38.8 (yes) Cs 77.0, K 23.0 −37.5 Ga 68.5, In 21.5, Sn 10 −19 no K 76.7, Na 23.3 −12.7 yes K 78.0, Na 22.0 −11 no Ga 61, In 25, Sn 13, Zn 1 8.5 yes Ga 62.5, In 21.5, Sn 16.0 10.7 yes Ga 69.8, In 17.6, Sn 12.5 10.8 no Ga 75.5, In 24.5 15.7 yes

Preferred Embodiment Restriction Plug Element with a First Composition Surrounding Second Composition (4200-4300)

A cross section of the present invention may be seen in more detail as generally illustrated in FIG. 42 (4200), wherein a restriction plug element (RPE) comprises a first composition (4201) that is in direct contact with a second composition (4202). The first composition (4201) surrounds a hollow second composition (4202). According to a preferred exemplary embodiment, the second composition changes phase, strength, or elasticity to deform the RPE, thereby shrinking its size. A reduced size RPE enables it to pass through a restriction sleeve member (RSM) when flowed or pumped back to the surface. The first composition (4201) and the second composition (4202) may be selected from a group of materials as aforementioned. The thickness of the hollow second composition is designed such that the RPE has the strength, shape and integrity to sustain high pressure conditions for the time period required to fracture its assigned zone. In one embodiment, this time period is approximately 10 to 12 hours. The thickness may also be selected such that volume shrinkage created by a phase, strength, or elasticity change in the second composition (4202) is compensated by the hollow space in the second composition (4202).

According to another preferred exemplary embodiment, the second composition (4202) may change phase, strength, or elasticity when exposed to the wellbore temperature conditions, in a controlled fashion. The first composition (4201) may control the rate of phase, strength, or elasticity change in the second composition (4202). In one preferred exemplary embodiment, the first composition may be an insulator such as ceramic, elastomer or plastic that surrounds the second composition and slows the rate at which the second composition changes phase. In another preferred exemplary embodiment, the first composition may be a conductor such as steel, stainless steel, aluminum, and copper that accelerates the rate of phase, strength, or elasticity change. The selection of second composition may depend on the temperature profile of the well.

In some wells that may be under higher temperature conditions than others, a higher melting point eutectic alloy may be used as a second composition in the RPE. According to another preferred exemplary embodiment, the second composition (4202) in the RPE may be tailored to adapt to the temperature profile of the wellbore conditions. Furthermore, the RPEs comprising second composition (4202) with different melting point temperature materials may be used in higher or lower temperature fracturing stages of the wellbore accordingly. For example, an RPE comprising a second composition with a melting point greater than 150° F. may be used in fracturing stage that has a wellbore temperature of 150° F. Similarly, an RPE comprising a second composition with a melting point of greater than 250° F. may be used in fracturing stage that has a wellbore temperature of 250° F.

According to another preferred exemplary embodiment, the RPE is shaped as a sphere, a cylinder or a dart. The first composition (4201) is shaped in the form of a sphere surrounding a hollow spherical shaped second composition (4202). Likewise, the first composition (4201) may be shaped in the form of a cylinder surrounding a hollow cylindrical shaped second composition (4202). Similarly, the RPE may be shaped in the form of a dart. The dart may have a property (Phase, strength, elasticity) changeable first composition fins (7401) attached to a hollow/solid dart shaped second composition (7402). The hollow/solid dart shaped second composition (7402) may change phase, strength or elasticity, thereby deforming/collapsing the dart RPE.

According to yet another preferred exemplary embodiment, the RPE is shaped as a sphere, a cylinder or a dart. The first composition (4301) is shaped in the form of a sphere surrounding a solid core spherical shaped second composition (4302). Likewise, the first composition (4301) may be shaped in the form of a cylinder surrounding a solid core cylindrical shaped second composition (4302).

Preferred Embodiment Restriction Plug Element with a First Composition Surrounding Second Composition with a Passage Way (4400-4600)

A cross section of the present invention may be seen in more detail as generally illustrated in FIG. 44 (4400), wherein a restriction plug element (RPE) comprises a first composition (4401) that is in direct contact with a second composition (4402). The first composition (4401) surrounds a hollow second composition (4402). According to a preferred exemplary embodiment, the second composition changes phase to deform the RPE thereby shrinking its size. The RPE further comprises a passage way (4403) to provide a path for the second composition to change phase, strength, and/or elasticity and exit the RPE. The passage way (4403) could be designed such that it orients downwards facing the inner surface of the wellbore casing. The downward orientation may enable the second composition (4402) to exit the RPE by means of gravity upon phase change. The second composition may stay at the bottom of the wellbore casing during production without impeding production flow. Alternatively, the debris created by the second composition (4402) may be flowed back. A perspective view of the RPE is illustrated in FIG. 45 (4500).

Alternately, the second composition may exit the RPE by stress or pressure as illustrated in FIG. 46 a (4600). During production, pressure acts in the direction of production pushing the RPE towards the RSM in the production direction. The second composition (4602) exits or squeezes out of the RPE through the passage (4603), thereby deforming the RPE. This enables an increase in hydrocarbon fluid flow in the production direction. Similarly, during fracturing operation, pressure acts in the direction of injection on the RPE that is seated in the RSM. The second composition (4612) exits or squeezes out of the RPE through the passage (4613), thereby deforming the RPE.

Preferred Embodiment Restriction Plug Element with a Second Composition Surrounding First Composition (4700-4800)

A cross section of the present invention may be seen in more detail as generally illustrated in FIG. 47 (4700), wherein a restriction plug element (RPE) comprises a second composition (4702) in direct contact with a first composition (4701). The second composition (4702) surrounds a hollow first composition (4701). According to a preferred exemplary embodiment, the second composition may change phase (melt/vaporize) to exit the RPE thereby reducing the size of the RPE. For example, if the RPE is shaped as a sphere, the outer diameter of the RPE is reduced by the amount of the thickness of the second composition (4702). The thickness of the second composition (4702) may be reduced to quickly change phase and exit, for example for RPEs toward the heel end or for quicker screen outs. The thickness of the second composition (4702) is designed such that the overall strength, rigidity and integrity of the RPE along with the first composition (4701) can withstand the high pressure differential during fracturing treatment. The overall size of the RPE may be selected to adapt to the size of the RSM. For example, if the inner sleeve diameter (ISD) is 4.1 inches, overall RPE diameter could be made 4.2 inches, first composition diameter could be 3.5 inches and the thickness of the second composition could be 0.35 inches. Materials for the first composition (4701) and the second composition (4702) may be selected from the list of materials as aforementioned.

According to another preferred exemplary embodiment, the RPE is shaped as a sphere or a cylinder. The second composition (4702) is shaped in the form of a sphere surrounding a solid core spherical shaped first composition (4701). Likewise, the second composition (4702) may be shaped in the form of a cylinder surrounding a solid cylindrical shaped first composition (4701).

According to yet another preferred exemplary embodiment, the RPE is shaped as a sphere or a cylinder. The second composition (4801) is shaped in the form of a sphere surrounding a hollow spherical shaped first composition (4801). Likewise, the second composition (4802) may be shaped in the form of a cylinder surrounding a hollow cylindrical shaped first composition (4801).

Similarly, the RPE may be shaped in the form of a dart as shown in FIG. 73 (7300). The dart may have a property (Phase, strength, elasticity) changeable second composition fins (7302) attached to hollow/solid dart shaped first composition (7301). The fins (7302) may change phase, strength or elasticity, leaving the RPE with the solid/hollow first composition central dart core. The reduced size “finless” dart may then be flown back through the RSM's to the surface or pumped into the hydrocarbon formation enabling unrestricted production fluid flow.

As shown in FIG. 72 (7200) the fins (7201) of the dart shaped RPE may comprise a first composition similar to the dart core (7202). The RPE (7200) may change physical property such as phase, strength, elasticity due to conditions encountered in a wellbore. The changed RPE due to phase, strength or elasticity may then exit the wellbore in a toe ward direction or may be pumped back to the surface in a production direction.

Preferred Embodiment Restriction Plug Element with a First Composition, a Second Composition, and a Third Composition (4900)

As generally illustrated in the cross section of FIG. 49 (4900), a restriction plug element comprises a first composition (4901) in direct contact with a second composition (4902) that is in direct contact with a third composition (4903). The first composition (4901) surrounds the second composition (4902) which in turn surrounds the third composition (4903). A passage way (4904) may be designed to facilitate the exit for the second composition (4902) upon a phase change. Phase change in the second composition (4902) may be triggered by a change in the temperature of the wellbore or the RSM. According to a preferred exemplary embodiment, the RPE shrinks and reduces size so as to pass through a restriction sleeve member (RSM) during flow back or during production. The thickness of the first, second and third compositions may be designed to withstand the high pressure conditions during fracturing treatment. Materials for the first composition (4901) and the second composition (4902) may be selected from the list of materials as aforementioned. Material for the third composition may be for example Al or Mg or any other high strength metal or non-metal.

It should be noted that even though the RPE illustrated in FIG. 49 (4900) comprises 3 layers, multiple layers arranged in any combination may be used. For example, an RPE may be made with 2 layers of second composition alternately between 2 layers of first composition or a combination of first and third composition. It should be noted that the RPE in FIG. 49 (4900) is for illustration purposes only and should be construed as a limitation of the number of compositions and layers comprising the RPE.

Preferred Embodiment Restriction Plug Element with Axial Flow Channels (5000-5100)

As generally illustrated in the cross section of FIG. 50 (5000), a restriction plug element comprises a first composition (5001) in direct contact with a second composition (5002). The RPE is facilitated with flow channels in the first composition (5001). The RPE may be shaped in the shape of a sphere or cylinder. According to a preferred exemplary embodiment, the flow channels are filled with the second composition (5002). The flow channels may be cut and machined in an axial manner. The flow channels may take the shape of a cylinder, a tube, or an elongated wedge shape or combination thereof. For example, a horizontal flow channel (5003) may be cut in the x-axis direction and a vertical flow channel (5004) may be cut in the y-axis direction. It should be noted that the axes shown in FIG. 50 are for illustration purposes only and may not be construed as a limitation. Multiple axes may be cut in the RPE and filled with the second composition (5002) to provide multiple channels for production fluids to flow through during production. The axes may or may not be orthogonal to each other. In addition, the axes may or may not be aligned to each other.

According to a presently preferred exemplary embodiment, upon exposure to temperatures in a wellbore higher than the phase/strength/elasticity change temperature, the second composition in the flow channel changes phase (melt/vaporize) or weakens in strength, thereby exiting the RPE and creating vacant flow channels in the RPE. The first composition (5001) may maintain its shape and structure while the second composition (5002) exits. After a fracturing treatment and exodus of the second composition (5002), the RPE may disengage from a restriction sleeve member and position itself between RSMs. The RPE may also stay engaged in the RSM. During production, the vacated flow channels may facilitate production fluids to flow in the production direction. Additionally, the flow channels in the RSM may be used in conjunction with the flow channels in the RPE to provide substantially unobstructed production flow. It should be noted that fluids may take any path that is least resistant in the flow channels during production and are not limited to a specific flow channel, axis, or alignment. For example, horizontal flow channel (5003) may be an ingress path and vertical flow channel (5004) may be an egress path for fluids to flow through. Similarly, horizontal flow channel (5003) may be used as both an ingress and egress for fluid flow. A perspective view of the RPE is illustrated in more detail in FIG. 51 (5100).

Preferred Exemplary Wellbore Plug Isolation with Exemplary Restriction Plug Element Flowchart Embodiment (5200)

As generally seen in the flow chart of FIG. 52 (5200), preferred exemplary wellbore plug isolation with exemplary restriction plug element method may be generally described in terms of the following steps:

-   -   (1) checking if a restriction sleeve member (RSM) is already         integral to the casing, if so, proceeding to step (5203) (5201);         -   A temperature profile may be taken determine wellbore             temperature. The temperature profile may include wellbore             temperature after casing installation, before a RPE is             pumped, during a fracturing treatment and after a fracturing             treatment. A more specific profile could also be measured in             individual fracturing zones.     -   (2) setting a RSM at the desired wellbore location with a WST         (5202);         -   The WST could set the RSM with a power charge or pressure.     -   (3) perforating hydrocarbon formation with a perforating GSA         (5203);         -   The perforating GSA may perforate one interval at a time             followed by pulling the GSA and perforating the next             interval in the stage. The perforation operation is             continued until all the intervals in the stage are             completed.     -   (4) deploying an RPE to seat in the RSM isolating fluid         communication between upstream (heel or production end) of the         RSM and downstream (toe or injection end) of the RSM and         creating a hydraulic fracturing stage (5204);         -   RPE may be pumped from the surface, deployed by gravity, or             set by a tool. If a conforming seating surface (CSS) is             present in the RSM, the RPE may be seated in the CSS. A             Positive differential pressure may enable RPE to be driven             and locked into the RSM. The RPE may be at the temperature             of the RSM when it lands on the RSM. The temperature of the             RSM may be controlled using a fluid pumped from the surface             or with a cooling fluid channel integrated into the RSM.         -   The RPE comprising a first composition and a second             composition with a specific melting point range may be             selected, so that the melting point selected is greater than             the temperature of the fracture zone and wellbore             temperature. A higher phase change temperature second             composition may be deployed for higher temperature             fracturing zones. For example, an RPE comprising a second             composition with a melting point greater than 150° F. may be             used in fracturing stage that has a wellbore temperature of             150° F. Similarly, an RPE comprising a second composition             with a melting point of greater than 250° F. may be used in             fracturing stage that has a wellbore temperature of 250° F.     -   (5) maintaining RPE contact temperature to keep it from changing         phase (5205);         -   Fracturing fluids may be pumped along with the RPE or after             the RPE is pumped. The RPE may be at the same temperature as             the fracturing fluid. The temperature of the fracturing             fluids is controlled to maintain the RPE at a temperature             below the phase change temperature (melting point or boiling             point or sublimation point). The temperature and volume of             the fracturing fluids may be adjusted based on the             temperature profile of the wellbore. For example, a greater             volume of fracturing fluids may be required to displace and             exchange heat convectively with a greater amount of             hydrocarbon formations fluids already present in the             wellbore casing.     -   (6) fracturing the hydraulic fracturing stage (5205);         -   Hydraulic fracturing fluids are pumped at high pressure to             create pathways in hydrocarbon formations. During the             hydraulic fracturing process, the convective fracturing             fluid from the surface pumped to fracture the zone may also             serve as a coolant for the RPE relative to latent high             temperatures. Latent heat from the hydrocarbon formation may             be transferred by convection to the RPE and is in turn             transferred and removed from the RPE by convection to the             fracturing fluid. In addition, the fracturing fluid             displaces hydrocarbons within the well minimizing             hydrocarbon contact with the RPE, thereby inhibiting phase             change of the RPE during the hydraulic fracturing process.     -   (7) controlling RPE contact temperature to enable it to change         phase (5206);         -   Once the fracturing zone is complete, hotter fluids may be             pumped into the stage to effectively expose the portion of             the RPE to higher predetermined temperatures, greater than             the phase change temperature of the second composition of             the RPE, thereby initiating the phase change of the RPE.     -   (8) checking if all hydraulic fracturing stages in the wellbore         casing have been completed, if not so, repeating steps (5201) to         (5207) (5208); and         -   After fracturing a stage another RPE is deployed or pumped             to seat into a stage towards the heel end, and hydraulic             fracturing procedures in the respective zone are initiated.             The RPEs in the already fractured zones may be changing             phase to shrink/reduce size or open up flow channels. The             newly seated RPE functions to block fracturing fluid flow             from reaching the now phase changing lower RPE. Thus, the             RPEs of the already fractured stages towards the toe end of             the wellbore continue to phase change while the zones above             it are fractured. Without the relatively cool fracturing             fluid reaching the lower RPE, the lower RPEs temperature             will climb to the latent temperature in the wellbore. The             latent temperature in the wellbore can reach, for example,             in excess of 200° F., in excess of 220° F., or in excess of             350° F. The latent formation heat and pressure and             hydrocarbons from the formation function to accelerate the             phase change (melt/vaporize) the RPE and disengage the RPE             from the RSM.         -   Since the toe end fracturing stages with RPE's are exposed             to latent heat of the wellbore for longer periods of time as             compared to the RPE's towards the heel end fracturing             stages, a lower melting point RPE may be pumped into the             heel end fracturing stage and a higher melting point RPE may             be deployed towards the toe end facilitating a faster phase             change towards the heel end. According to a present             preferred exemplary embodiment, RPEs may be selected from a             range of melting points (phase change temperatures) for             fracturing stages in the toe end, middle and heel end such             that the overall cycle time is reduced for screen out and             flow back.     -   (9) enabling fluid flow in the production (heel end) direction         (5209);         -   The fluid flow in the production direction (heel end) may be             enabled through flow channels designed in the RSM while the             RPEs are positioned in between the RSMs; fluid flow may also             be enabled through flow channels designed in the RPEs. A             combination of flow channels in the RPE and RSM may enable             substantially unobstructed oil and gas flow. Alternatively             RPEs may also be removed from the wellbore casing or the             RPEs could be flowed back to surface, pumped into the             wellbore, or shrink in the presence of wellbore fluids or             acid. No intervention is needed to remove the RPE after its             useful life of isolating the pressure communication is             completed. Alternatively, the remainder of the RPE may be             pumped to the surface.

Preferred Embodiment Mechanical Toroid Restriction Plug Element with (5300-5700)

As generally illustrated in the cross section of FIG. 56 (5600), a restriction plug element comprises a first composition (5601) in direct contact with a second composition (5602). The first composition in the RPE may comprise multiple parts/segments that are held together by a toroid shaped un-bonded mechanical insert (5603). The RPE may be shaped as a sphere, cylinder, or ovoid. According to a preferred exemplary embodiment, the mechanical insert may be cast or die cast from second composition (5602). The toroid (5603) mechanical insert holds the RPE together during fracturing treatment. The mechanical insert may be designed such that the structure provides rigidity and strength to the RPE.

According to a preferred exemplary embodiment, the toroid mechanical insert may change phase (melt/vaporize) or loose strength or elasticity after a fracture treatment upon contact with wellbore formations or fluids pumped from the surface. The un-bonded mechanical linkage progressively weakens at well temperatures, allowing the ball to change shape in one or more coordinate directions, or to separate into multiple parts, whether or not the ball was in multiple parts before mechanically linked. The second composition may melt/vaporize and crumble the RPE into individual small segments like orange segments. The protrusions shown in FIG. 56 (5600) for toroid mechanical inserts are for illustration purposes only and may not be construed as a limitation. Multiple protrusions for the toroid insert may be created. Tradeoffs between number of protrusions, mechanical integrity and cost may be evaluated to determine an optimal structure. A cross section of a RPE with one protrusion in the toroid shape is illustrated in FIG. 57 (5700).

A perspective view of the restriction plug element with toroid mechanical insert is illustrated further in FIG. 53 (5300). A top and side perspective view of the restriction plug element with mechanical insert is illustrated in more detail in FIG. 54 (5400) and FIG. 55 (5500) respectively. Similarly, an exemplary embodiment oval shaped RPE with a toroid mechanical insert is illustrated in FIG. 57 a (5720).

Preferred Embodiment Sliding Piston Restriction Plug Element (5800-6200)

As generally illustrated in the cross section of FIG. 60 (6000), a restriction plug element comprises a first composition (6001) in contact with a second composition (6002). The RPE is facilitated with flow channels in the first composition (6001). The RPE may be shaped as a sphere or a cylinder. Flow channels (6003) may be cut in the RPE. The flow channels (6003) may be hollow tubular, cylindrical, wedge shaped, or combinations thereof. The RPE may further comprise a sliding piston (6005) that slides from a first position to a second position. The second composition (6002) may clamp the piston in first position. Upon a phase change in the second composition (6002), the piston (6005) may slide from the first position to a second position in an annular space (6004). The second composition (6002) may melt/vaporize (change phase) on reaching its phase change temperature upon contact with wellbore fluids or fluids pumped from the surface. Pursuant to phase change in the second composition (6002), the piston (6005) loses hold and may slide to the second position. According to a preferred exemplary embodiment, in the second position the piston may align an aperture (6006) with the flow channels (6003) to enable fluid communication with the hydrocarbon formation during production. According to another exemplary embodiment, the piston (6005) in the first position holds in place while blocking fluid communication with toe end fracturing zones. In yet another exemplary embodiment, the piston may be made of the second composition (6002) and completely melt/vaporize subsequent to fracturing treatment creating flow channels in the RPE.

A perspective view of the restriction plug element with a sliding piston is illustrated further in FIG. 58 (5800). A side perspective view of the restriction plug element with a sliding piston is illustrated in more detail in FIG. 59 (5900). A perspective view of the piston (6005) is illustrated in more detail in FIG. 61 (6100) and FIG. 62 (6200).

Preferred Embodiment Restriction Plug Element with Internal Flow Channels (6400, 6700, 7000)

As generally illustrated in FIG. 64 (6400), a cylindrical restriction plug element comprises a first composition (6401) in direct contact with a second composition (6402). The RPE is facilitated with flow channels in the first composition (6401). The RPE may be shaped as a sphere, cylinder, ovoid or dart. According to a preferred exemplary embodiment, the flow channels are filled with the second composition (6402). The flow channels may be cut through the first composition. The flow channels may take the shape of a cylinder, a tube, or an elongated wedge shape or combination thereof.

According to a presently preferred exemplary embodiment, upon exposure to temperatures in a wellbore higher than the phase/strength/elasticity change temperature, the second composition in the flow channel changes phase (melt/vaporize) or weakens in strength/elasticity, thereby exiting the RPE and creating vacant flow channels in the RPE. The first composition (6401) may maintain its shape and structure while the second composition (6402) exits. After a fracturing treatment and exodus of the second composition (6402), the RPE may disengage from a restriction sleeve member and position itself between RSMs. The RPE may also stay engaged in the RSM. During production, the vacated flow channels may facilitate production fluids to flow in the production direction. Additionally, the flow channels in the RSM may be used in conjunction with the flow channels in the RPE to provide substantially unobstructed production flow. It should be noted that fluids may take any path that is least resistant in the flow channels during production and are not limited to a specific flow channel, axis, or alignment.

Similarly, an exemplary embodiment ovoid RPE is illustrated in FIG. 67 (6700) comprises a first composition (6701) in direct contact with a second composition (6702). Likewise, an exemplary embodiment dart RPE is illustrated in FIG. 70 (7000) comprises a first composition (7001) in direct contact with a second composition (7002).

According to an exemplary embodiment, the first composition and second composition may be reversed. For example, the internal flow channels may be filled with first composition surrounded by a second composition. In this case, the overall size of the RPE diminishes as the second compositions changes property (phase/strength/elasticity) enabling substantially larger fluid flow during production.

Preferred Embodiment Restriction Plug Element with External Flow Channels (6300, 6600, 6900)

According to another exemplary embodiment, the flow channels may be exterior to the RPE. As generally illustrated in FIG. 63 (6300), a cylindrical restriction plug element comprises a first composition (6301) in direct contact with a second composition (6302). The RPE is facilitated with outer flow channels in the first composition (6301). The RPE may be shaped as a sphere, cylinder, ovoid or dart. According to a preferred exemplary embodiment, the flow channels may or may not be filled with a second composition (6302). The flow channels may be cut through the first composition. The flow channels may take the shape of a cylinder, a tube, or an elongated wedge shape or combination thereof.

According to a presently preferred exemplary embodiment, upon exposure to temperatures in a wellbore higher than the phase/strength/elasticity change temperature, the second composition in the flow channel changes phase (melt/vaporize) or weakens in strength, thereby exiting the RPE and creating vacant flow channels in the RPE. The first composition (6301) may maintain its shape and structure while the second composition (6302) exits.

Similarly, an exemplary embodiment ovoid RPE is illustrated in FIG. 66 (6600) that comprises a first composition (6601) in direct contact with a second composition (6602). Likewise, an exemplary embodiment dart RPE is illustrated in FIG. 69 (6900) that comprises a first composition (6901) in direct contact with a second composition (6902).

According to an exemplary embodiment, the first composition and second composition may be reversed. For example, the internal flow channels may be filled with first composition surrounded by a second composition. In this case, the overall size of the RPE diminishes as the second compositions changes property (phase/strength/elasticity) enabling substantially larger fluid flow during production.

Preferred Embodiment Restriction Plug Element with Banded Flow Channels (6500, 6800, 7100)

According to another exemplary embodiment, the flow channels may be banded in the RPE. As generally illustrated in FIG. 65 (6500), a cylindrical restriction plug element comprises a first composition (6501) in direct contact with a second composition (6502). The RPE is facilitated with banded flow channels in the first composition (6501). The RPE may be shaped in the shape of a sphere, cylinder, ovoid or dart. According to a preferred exemplary embodiment, the flow channels may or may not be filled with a second composition (6502). The flow channels may be cut through the first composition. The flow channels may take the shape of a cylinder, a tube, or an elongated wedge shape or combination thereof.

According to a presently preferred exemplary embodiment, upon exposure to temperatures in a wellbore higher than the phase/strength/elasticity change temperature, the second composition in the flow channel changes phase (melt/vaporize) or weakens in strength, thereby exiting the RPE and creating vacant flow channels in the RPE. The first composition (6501) may maintain its shape and structure while the second composition (6502) exits.

Similarly, an exemplary embodiment ovoid RPE is illustrated in FIG. 68 (6800) that comprises a first composition (6801) in direct contact with a second composition (6802). Likewise, an exemplary embodiment dart RPE is illustrated in FIG. 71 (7100) that comprises a first composition (7101) in direct contact with a second composition (7102).

According to an exemplary embodiment, the first composition and second composition may be reversed. For example, the internal flow channels may be filled with first composition surrounded by a second composition. In this case, the overall size of the RPE diminishes as the second compositions changes property (phase/strength/elasticity) enabling substantially larger fluid flow during production.

Temperature Profile in a Wellbore (7400)

A typical temperature profile in a wellbore is shown in the plot (7400). The plot shows a time (x-axis) (7401) plotted against a temperature (y-axis) (7402) in the wellbore. The temperature of the RSM may be at constant temperature (for example 150° F.) before fracturing treatment (7403) in a zone. The temperature may rise to 190° F. during fracturing operation (7404) and further increase to 250° F. after fracturing treatment (7405) and stay at the temperature during production (7406). The temperature profile may be used to select RPEs with a specific melting point, strength, or phase changing temperature.

System Summary

The present invention system anticipates a wide variety of variations in the basic theme of extracting gas utilizing wellbore casings, but can be generalized as a wellbore isolation plug system comprising:

-   -   (a) restriction sleeve member (RSM); and     -   (b) restriction plug element (RPE);     -   wherein     -   the RSM is configured to fit within a wellbore casing;     -   the RSM is configured to be positioned at a desired wellbore         location by a wellbore setting tool (WST);     -   the WST is configured to set and form a seal between the RSM and         an inner surface of the wellbore casing to prevent substantial         movement of the RSM; and     -   the RPE is configured to position to seat in the RSM.

This general system summary may be augmented by the various elements described herein to produce a wide variety of invention embodiments consistent with this overall design description.

Method Summary

The present invention method anticipates a wide variety of variations in the basic theme of implementation, but can be generalized as a wellbore plug isolation method wherein the method is performed on a wellbore plug isolation system comprising:

-   -   (a) restriction sleeve member (RSM); and     -   (b) restriction plug element (RPE);     -   wherein     -   the RSM is configured to fit within a wellbore casing;     -   the RSM is configured to be positioned at a desired wellbore         location by a wellbore setting tool (WST);     -   the WST is configured to set and form a seal between the RSM and         an inner surface of the wellbore casing to prevent substantial         movement of the RSM; and     -   the RPE is configured to position to seat in the RSM;     -   wherein the method comprises the steps of:     -   (1) installing the wellbore casing;     -   (2) deploying the WST along with the RSM and a perforating gun         string assembly (GSA) to a desired wellbore location in the         wellbore casing;     -   (3) setting the RSM at the desired wellbore location with the         WST and forming a seal;     -   (4) perforating the hydrocarbon formation with the perforating         GSA;     -   (5) removing the WST and perforating GSA from the wellbore         casing;     -   (6) deploying the RPE into the wellbore casing to seat in the         RSM and creating a hydraulic fracturing stage;     -   (7) fracturing the stage with fracturing fluids;     -   (8) checking if all hydraulic fracturing stages in the wellbore         casing have been completed, if not so, proceeding to the step         (2);     -   (9) enabling fluid flow in production direction; and     -   (10) commencing oil and gas production from the hydraulic         fracturing stages.

This general method summary may be augmented by the various elements described herein to produce a wide variety of invention embodiments consistent with this overall design description.

System/Method Variations

The present invention anticipates a wide variety of variations in the basic theme of oil and gas extraction. The examples presented previously do not represent the entire scope of possible usages. They are meant to cite a few of the almost limitless possibilities.

This basic system and method may be augmented with a variety of ancillary embodiments, including but not limited to:

-   -   An embodiment wherein said WST is further configured to form a         conforming seating surface (CSS) in said RSM; and said RPE is         configured in complementary shape to said CSS shape to seat to         seat in said CSS.     -   An embodiment wherein a conforming seating surface (CSS) is         machined in said RSM; and said RPE is configured in         complementary shape to said CSS shape to seat to seat in said         CSS.     -   An embodiment wherein the WST grips the RSM to the inside of the         casing with gripping elements selected from a group consisting         of: elastomers, carbide buttons, and wicker forms.     -   An embodiment wherein said RSM is degradable.     -   An embodiment wherein said RPE is degradable.     -   An embodiment wherein said RSM material is selected from a group         consisting of: aluminum, iron, steel, titanium, tungsten,         copper, bronze, brass, plastic, and carbide.     -   An embodiment wherein said RPE material is selected from a group         consisting of: a metal, a non-metal, and a ceramic.     -   An embodiment wherein said RPE shape is selected from a group         consisting of: a sphere, a cylinder, and a dart.     -   An embodiment wherein         -   said wellbore casing comprises an inner casing surface (ICS)             associated with an inner casing diameter (ICD);         -   said RSM comprises an inner sleeve surface (ISS) associated             with an inner sleeve diameter (ISD); and         -   ratio of said ISD to said ICD ranges from 0.5 to 0.99.     -   An embodiment wherein said plural RPEs are configured to create         unevenly spaced hydraulic fracturing stages.     -   An embodiment wherein said RPE is not degradable;         -   said RPE remains in between RSMs; and         -   fluid flow is enabled through flow channels the RSMs in             production direction.     -   An embodiment wherein said RPE is not degradable; and said RPE         is configured to pass through said RSMs in the production         direction.     -   An embodiment wherein the WST sets the RSM to the inside surface         of the wellbore casing at multiple points of the RSM.     -   An embodiment wherein said inner sleeve surface of said RSM         comprises polished bore receptacle (PBR).

One skilled in the art will recognize that other embodiments are possible based on combinations of elements taught within the above invention description.

Restriction Plug Element System Summary

The present invention system anticipates a wide variety of variations in the basic theme of extracting gas utilizing wellbore casings, but can be generalized as a restriction plug element in a wellbore isolation plug system comprising:

-   -   (a) first composition; and     -   (b) second composition     -   wherein     -   the first composition and the second composition are in direct         contact with each other; and     -   the second composition is configured to change phase at a         predetermined temperature expected to be encountered in the         wellbore.

This general system summary may be augmented by the various elements described herein to produce a wide variety of invention embodiments consistent with this overall design description.

Alternate Restriction Plug Element System Summary

The present invention system anticipates a wide variety of variations in the basic theme of extracting gas utilizing wellbore casings, but can be generalized as a restriction plug element in a wellbore isolation plug system comprising:

-   -   (a) restriction sleeve member (RSM); and     -   (b) restriction plug element (RPE)     -   wherein     -   the RSM is configured to fit within a wellbore casing;     -   the RSM is configured to be positioned at a wellbore location by         a wellbore setting tool (WST);     -   the RPE is configured to position to seat in the RSM;     -   the RPE comprises a first composition and a second composition;     -   the first composition and the second composition are in direct         contact with each other; and     -   the second composition is configured to phase change at a         predetermined temperature expected to be encountered in the         wellbore casing.

This general system summary may be augmented by the various elements described herein to produce a wide variety of invention embodiments consistent with this overall design description.

Restriction Plug Element Method Summary

The present invention method anticipates a wide variety of variations in the basic theme of implementation, but can be generalized as a wellbore plug isolation method wherein the method is performed on a wellbore plug isolation system with a restriction plug element comprising:

-   -   (a) first composition; and     -   (b) second composition     -   wherein     -   the first composition and the second composition are in direct         contact with each other; and     -   the second composition is configured to change phase at a         predetermined temperature expected to be encountered in the         wellbore;     -   wherein the method comprises the steps of:     -   (1) checking if a restriction sleeve member (RSM) is present, if         so, proceeding to step (3);     -   (2) setting a RSM at a wellbore location in a wellbore casing;     -   (3) perforating a hydrocarbon formation with a perforating gun         string assembly;     -   (4) deploying the RPE into the wellbore casing to isolate toe         end fluid communication and create a hydraulic fracturing stage;     -   (5) controlling the RPE contact temperature to maintain a phase         in the second composition;     -   (6) fracturing the fracturing stage with fracturing fluids;     -   (7) controlling the RPE contact temperature to enable the second         composition to undergo phase change;     -   (8) checking if all hydraulic fracturing stages in the wellbore         casing have been completed, if not so, repeating steps (1) to         (7); and     -   (9) enabling fluid flow in production direction.

This general method summary may be augmented by the various elements described herein to produce a wide variety of invention embodiments consistent with this overall design description.

Restriction Plug Element System/Method Variations

The present invention anticipates a wide variety of variations in the basic theme of oil and gas extraction. The examples presented previously do not represent the entire scope of possible usages. They are meant to cite a few of the almost limitless possibilities.

This basic system and method may be augmented with a variety of ancillary embodiments, including but not limited to:

-   -   An embodiment wherein the first composition at least partially         surrounds the second composition.     -   An embodiment wherein the second composition at least partially         surrounds the first composition.     -   An embodiment wherein upon phase change the second composition         exits the RPE thereby forming at least one flow channel in the         RPE.     -   An embodiment wherein when the second composition changes phase,         the RPE deforms to enable it to pass through a restriction         sleeve member in the wellbore.     -   An embodiment wherein when the second composition changes phase,         the RPE reduces size to enable it to pass through a restriction         sleeve member in the wellbore.     -   An embodiment wherein the phase change comprises a change from         solid to liquid.     -   An embodiment wherein the phase change comprises a change from         solid to gas.     -   An embodiment wherein the phase change comprises a change from         liquid to gas.     -   An embodiment wherein the second composition is in further         direct contact with a third composition.     -   An embodiment wherein the second composition at least partially         surrounds a solid core of the third composition.     -   An embodiment wherein the second composition at least partially         surrounds a hollow core of the third composition.     -   An embodiment wherein when the second composition changes phase,         the second composition exits the RPE through a passage in the         first composition.     -   An embodiment wherein the flow channels are configured to enable         substantially unobstructed fluid flow during production.     -   An embodiment wherein at least some of the flow channels are         aligned with each other.     -   An embodiment wherein the flow channels further comprise         toroidal forms.     -   An embodiment wherein the flow channels further comprise a         piston, wherein the piston is configured to slide from a first         position to a second position to enable fluid flow through the         flow channels.     -   An embodiment wherein the first composition is selected from a         group comprising plastics, non-degradable or long term         degradable.     -   An embodiment wherein the second composition is selected from a         group comprising eutectic metals, non-eutectic metals or         thermoplastics.     -   An embodiment wherein the first composition controls a rate of         change of phase of the second composition.     -   An embodiment wherein the second composition is selected to         change phase under wellbore temperature conditions.     -   An embodiment wherein the phase change in the second composition         is temperature dependent.     -   An embodiment further comprises a heating element, the heating         element upon activation accelerates the phase change of the         second composition.     -   An embodiment wherein the first composition surrounds a solid         spherical core of the second composition.     -   An embodiment wherein the first composition surrounds a hollow         spherical core of the second composition.     -   An embodiment wherein the first composition surrounds a solid         cylindrical core of the second composition.     -   An embodiment wherein the first composition surrounds a hollow         cylindrical core of the second composition.

CONCLUSION

A wellbore plug isolation system and method for positioning plugs to isolate fracture zones in a horizontal, vertical, or deviated wellbore has been disclosed. The system/method includes a wellbore casing laterally drilled into a hydrocarbon formation, a wellbore setting tool (WST) that sets a large inner diameter (ID) restriction sleeve member (RSM), and a restriction plug element (RPE). The RPE includes a first composition and a second composition that changes phase or strength under wellbore conditions. After a stage is perforated, RPEs are deployed to isolate toe ward pressure communication. The second composition changes phase to create flow channels in the RPE during production. In an alternate system/method, the second composition changes phase or strength thereby deforming the RPE to reduce size and pass through the RSM's. The RPEs are removed or left behind prior to initiating well production without the need for a milling procedure. 

1. A restriction plug element (RPE) in a wellbore system comprising: (a) first composition; and (b) second composition wherein said first composition and said second composition are proximal to each other; said second composition is configured to change a physical property at a predetermined temperature expected to be encountered in said wellbore without chemically reacting with wellbore fluids in said wellbore; and said physical property selected from a group consisting of: phase, strength, and elasticity.
 2. The restriction plug element of claim 1 wherein said first composition at least partially surrounds said second composition.
 3. The restriction plug element of claim 1 wherein said second composition at least partially surrounds said first composition.
 4. The restriction plug element of claim 2 wherein as said second composition changes physical property, said second composition exits said restriction plug element to form at least one flow channel in said restriction plug element.
 5. The restriction plug element of claim 2 wherein as said second composition changes physical property, said restriction plug element deforms such that said restriction plug element passes through a restriction sleeve member in said wellbore.
 6. The restriction plug element of claim 3 wherein as said second composition changes physical property, said restriction plug element reduces size to enable it to pass through a restriction sleeve member in said wellbore.
 7. (canceled)
 8. (canceled)
 9. (canceled)
 10. The restriction plug element of claim 2 wherein said second composition is in further direct contact with a third composition.
 11. The restriction plug element of claim 10 wherein said second composition at least partially surrounds a solid core of said third composition.
 12. The restriction plug element of claim 10 wherein said second composition at least partially surrounds a cavity of said third composition.
 13. The restriction plug element of claim 2 wherein as said second composition changes physical property, said second composition exits said restriction plug element through a passage in said first composition.
 14. The restriction plug element of claim 4 wherein said flow channels are configured to enable substantially unobstructed fluid flow during production.
 15. The restriction plug element of claim 4 wherein at least some of said flow channels are aligned with each other.
 16. The restriction plug element of claim 4 wherein said flow channels further comprise a piston, wherein said piston is configured to slide from a first position to a second position to enable fluid flow through said flow channels.
 17. The restriction plug element of claim 1 wherein said first composition is selected from a group comprising plastics, non-degradable or long term degradable.
 18. The restriction plug element of claim 1 wherein said second composition is selected from a group comprising eutectic metals, non-eutectic metals or thermoplastics.
 19. The restriction plug element of claim 1 wherein said first composition controls a rate of temperature change of said second composition.
 20. The restriction plug element of claim 1 wherein said second composition is selected to change phase under wellbore temperature conditions.
 21. The restriction plug element of claim 1 wherein said change in physical property of said second composition is temperature dependent.
 22. The restriction plug element of claim 1 further comprises a heating element, said heating element upon activation accelerates said change in physical property of said second composition.
 23. The restriction plug element of claim 1 wherein said first composition surrounds a solid spherical core of said second composition.
 24. The restriction plug element of claim 1 wherein said first composition surrounds a hollow spherical core of said second composition.
 25. The restriction plug element of claim 1 wherein said first composition surrounds a solid cylindrical core of said second composition.
 26. The restriction plug element of claim 1 wherein said first composition partially surrounds a hollow cylindrical core of said second composition.
 27. A wellbore plug isolation system comprising: (a) restriction sleeve member (RSM); and (b) restriction plug element (RPE) wherein said RSM is configured to fit within a wellbore casing; said RSM is configured to be positioned at a wellbore location by a wellbore setting tool (WST); said RPE is configured to position to seat in said RSM; said RPE comprises a first composition and a second composition; said first composition and said second composition are in direct contact with each other; said second composition is configured to change a physical property at a predetermined temperature expected to be encountered in said wellbore casing without chemically reacting with wellbore fluids in said wellbore; and said physical property selected from a group consisting of: phase, strength, and elasticity.
 28. A wellbore plug isolation method, said method operating in conjunction with a restriction plug element (RPE), said restriction plug element comprising: (a) first composition; and (b) second composition wherein said first composition and said second composition are in direct contact with each other; said second composition is configured to change a physical property at a predetermined temperature expected to be encountered in said wellbore without chemically reacting with wellbore fluids in said wellbore; and said physical property selected from a group consisting of: phase, strength, and elasticity. wherein said method comprises the steps of: (1) checking if a restriction sleeve member (RSM) is present, if so, proceeding to step (3); (2) setting a restriction sleeve member at a wellbore location in a wellbore casing; (3) perforating a hydrocarbon formation with a perforating gun string assembly; (4) deploying said restriction plug element into said wellbore casing to isolate toe end fluid communication and create a hydraulic fracturing stage; (5) controlling a contact temperature of said restriction plug element to maintain said physical property of said second composition; (6) fracturing said fracturing stage with fracturing fluids; (7) controlling a contact temperature of said restriction plug element to enable said second composition to undergo a change in said physical property; (8) checking if all hydraulic fracturing stages in said wellbore casing have been completed, if not so, repeating steps (1) to (7); and (9) enabling fluid flow in production direction.
 29. The wellbore plug isolation method of claim 28 wherein said first composition at least partially surrounds said second composition.
 30. The wellbore plug isolation method of claim 28 wherein said second composition at least partially surrounds said first composition. 